Showing papers on "Myoglobin published in 2011"
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TL;DR: Two methods for processing raw UV-vis spectroscopic data generated from the Mb-CO assay are presented and comprehensively discussed here for the first time.
Abstract: The deoxy-myoglobin (deoxy-Mb)/carbonmonoxy-myoglobin (Mb-CO) UV-vis assay is the principal method used for quantifying the rates of CO release from CO-releasing molecules (CO-RMs) that might possess therapeutic benefits. Some issues emerge when the Mb-CO assay is utilized for testing CO-RMs with novel structures, which are comprehensively discussed here for the first time. Two methods for processing raw UV-vis spectroscopic data generated from the assay are presented in this paper.
150 citations
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TL;DR: In this paper, the authors used direct electron transfer between the Fe(III)-heme and the electrode surface that was modified with metal nanoparticles stabilized by didodecyldimethylammonium bromide and antibodies.
Abstract: Cardiac myoglobin detection was based on direct electron transfer between the Fe(III)-heme and the electrode surface that was modified with metal nanoparticles stabilized by didodecyldimethylammonium bromide and antibodies. Gold, silver and copper nanoparticles were tested as catalysts of the Fe(III)/Fe(II) electrode process. All experiments were carried out with human blood plasma samples of healthy donors and patients with acute myocardial infarction. The method proposed does not require labeled secondary antibodies. Immunosensor has a detection limit of 5 ng/mL and a broad range of working concentrations. The whole procedure takes 20 minutes and can be used to establish the diagnosis of acute myocardial infarction.
73 citations
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TL;DR: Myoglobin is present in the murine vasculature and contributes significantly to nitrite-induced vasodilation, which is confirmed to confirm the presence of myoglobin in murine aortic tissue and to test the hypothesis that vascular wall myoglobin is important for nitite-induced Vasodilation.
Abstract: Aims This work investigates the role of myoglobin in mediating the vascular relaxation induced by nitrite. Nitrite, previously considered an inert by-product of nitric oxide metabolism, is now believed to play an important role in several areas of pharmacology and physiology. Myoglobin can act as a nitrite reductase in the heart, where it is plentiful, but it is present at a far lower level in vascular smooth muscle—indeed, its existence in the vessel wall is controversial. Haem proteins have been postulated to be important in nitrite-induced vasodilation, but the specific role of myoglobin is unknown. The current study was designed to confirm the presence of myoglobin in murine aortic tissue and to test the hypothesis that vascular wall myoglobin is important for nitrite-induced vasodilation.
Methods and results Aortic rings from wild-type and myoglobin knockout mice were challenged with nitrite, before and after exposure to the haem-protein inhibitor carbon monoxide (CO). CO inhibited vasodilation in wild-type rings but not in myoglobin-deficient rings. Restitution of myoglobin using a genetically modified adenovirus both increased vasodilation to nitrite and reinstated the wild-type pattern of response to CO.
Conclusion Myoglobin is present in the murine vasculature and contributes significantly to nitrite-induced vasodilation.
59 citations
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TL;DR: Postmortem pH and myoglobin played an essential role in lipid oxidation and off odor in fish muscle during the extended storage and the prime quality of fish with a negligible fishy odor could be maintained during postharvest handling or storage.
Abstract: The effect of pH (6.0, 6.5, and 7.0) on lipid oxidation in washed Asian seabass (Lates calcarifer) mince mediated by oxymyoglobin from the dark muscle of little Eastern tuna (Euthynnus affinis) during 8 d of refrigerated storage was studied. Metmyoglobin formation and discoloration increased with increasing storage time and the changes were more pronounced at lower pH. The highest lipid oxidation and off-odor development were observed when myoglobin was incorporated in washed mince at pH 6.0. At low pH, oxidation of myoglobin took place and lipid oxidation in washed mince was enhanced. This was concomitant with the increased fishy and rancid off odor in the sample containing myoglobin, especially at pH 6.0. Washed mince containing myoglobin at pH 6.0 had 1-octen-3-ol and hexanal as the major volatile compounds. Thus, postmortem pH and myoglobin played an essential role in lipid oxidation and off odor in fish muscle during the extended storage.
Practical Application: Myoglobin plays a role in the color of fish muscle. The change of myoglobin affects not only consumer acceptability, but also lipid oxidation as well as odor. The control of pH of muscle could be a potential means to lower the lipid oxidation mediated by myoglobin. As a consequence, the prime quality of fish with a negligible fishy odor could be maintained during postharvest handling or storage.
52 citations
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TL;DR: The use of magnetic circular dichroism and electronic absorption spectroscopy is reviewed to characterize nitrogen-, oxygen-, and sulfur-donor-ligated H93G Mb adducts with an emphasis on species not easily prepared by other heme model system approaches and those that serve as spectroscopic models for native heme proteins.
50 citations
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TL;DR: An artificial long-lived photoinduced charge-separation system using a protein crystal with different redox cofactors fixed in defined locations is constructed and the results suggest that these features are governed by steric repulsion and electrostatic interaction induced by amino acid residues located on the internal surface of the crystal lattices.
Abstract: Photoinduced electron transfer (ET) in native photosynthesis reactions is efficiently achieved by the accumulation of different types of redox cofactors within protein assemblies immobilized in cell membranes. The precise arrangement of each cofactor in the molecular spaces enables them to retain the long-lived charge-separated state, which promotes multistep reactions in biological systems. To elucidate the mechanism of the biological ETreactions and to develop light energy conversion systems, artificial ET proteins have been constructed using de novo proteins, chemical modification of native cofactors, photocatalytic reaction centers engineered into protein assemblies, and design of synthetic metal complexes immobilized in protein–protein ET systems. The reported systems have provided insights into control of ET rates in terms of the distance between donors and acceptors, hydrogen-bonding interactions, reorganization energy of cofactors, and other factors. Control of the dense accumulation of the different redox cofactors observed in natural photosystems required to achieve long-lived charge-separated state has caused difficulties in efforts to duplicate this process using artificial protein systems in solution. Thus, the design of novel protein frameworks that allow construction of a dense array of various cofactors is a worthwhile goal. Protein crystals can be regarded as excellent candidates for the development of artificial ET reaction systems because the crystal lattices are expected to allow different types of cofactors to be arranged in three-dimensional frameworks that mimic the native ET systems. ET reactions in single protein crystals have been investigated for the dependence of long-range ET on the structures and orientations of redox centers within proteins. Gray et al. constructed photochemically-initiated protein–protein ET reactions in protein crystals containing zinc-substituted cytochrome c peroxidase or ruthenium-modified azurin. Moreover, protein crystals provide nanosized spaces for the fixation of metal ions, metal complexes, and the diffusion of organic molecules. For instance, accumulation of metal ions and metal complexes in a protein crystal lattice spaces was accomplished simply by soaking of the crystals in a solution containing their precursors. Anisotropic diffusion of small molecules in hen egg-white lysozyme (HEWL) crystals has been investigated by experimental and simulation approaches. 22] The results suggest that these features are governed by steric repulsion and electrostatic interaction induced by amino acid residues located on the internal surface of the crystal lattices. Thus, if we can precisely arrange donor and acceptor molecules and mediators in protein crystals, it is expected that the novel three-dimensional framework will allow us to achieve a longlived charge-separated state. Herein, we construct an artificial long-lived photoinduced charge-separation system using a protein crystal with different redox cofactors fixed in defined locations. We demonstrate the photoinduced multistep ET in a sperm whale myoglobin (Mb) single crystal. Methyl viologen (MV)mediated ET occurs in the crystal between zinc porphyrin (ZnP; electron donor) and an oxo-centered triruthenium cluster (Ru3O; electron acceptor; Scheme 1). The Mb crystals with space group P6 form several channel structures (diameter 2–4 nm), which provide enough space for accumulation of nanosized functional molecules as previously reported. The Mb crystal spaces are available for site-specific fixation of Ru3O and anisotropic diffusion of MV. Moreover, fixation of zinc porphyrin units with a light-harvesting function in the Mb crystal is achieved by crystallization of zinc porphyrin substituted myoglobin (ZnMb). Our engineered Mb crystals, in which ZnP and Ru3O clusters are fixed at specific sites and which allow MV molecules to diffuse, contribute to providing the extremely long half-life of the final charge-separated state (ZnPC-Ru3O ), which is 2800 times longer than that of a previously reported model system in organic solution. This [*] Dr. T. Koshiyama, Dr. M. Shirai, Prof. Dr. K. Tanaka, Prof. Dr. S. Kitagawa, Prof. Dr. T. Ueno Institute for Integrated Cell-Material Sciences (iCeMS) Kyoto University iCeMS Lab Funai Center, Kyoto University Katsura Nishikyo-ku, Kyoto 615-8510 (Japan) Fax: (+ 81)75-383-2812 E-mail: kitagawa@icems.kyoto-u.ac.jp taka@icems.kyoto-u.ac.jp
50 citations
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TL;DR: Enhanced peroxygenase activity was observed for the mutant myoglobin with the single-winged cofactor, thus indicating that introduction of an artificial substrate-binding domain at only one of the heme propionates in the H64D mutant is the optimal engineering strategy for improving the peroxidase activity of myoglobin.
Abstract: H64D myoglobin mutant was reconstituted with two different types of synthetic hemes that have aromatic rings and a carboxylate-based cluster attached to the terminus of one or both of the heme-propionate moieties, thereby forming a "single-winged cofactor" and "double-winged cofactor," respectively. The reconstituted mutant myoglobins have smaller K(m) values with respect to 2-methoxyphenol oxidation activity relative to the parent mutant with native heme. This suggests that the attached moiety functions as a substrate-binding domain. However, the k(cat) value of the mutant myoglobin with the double-winged cofactor is much lower than that of the mutant with the native heme. In contrast, the mutant reconstituted with the single-winged cofactor has a larger k(cat) value, thereby resulting in overall catalytic activity that is essentially equivalent to that of the native horseradish peroxidase. Enhanced peroxygenase activity was also observed for the mutant myoglobin with the single-winged cofactor, thus indicating that introduction of an artificial substrate-binding domain at only one of the heme propionates in the H64D mutant is the optimal engineering strategy for improving the peroxidase activity of myoglobin.
48 citations
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TL;DR: The study shows that it is essential to do a time/dose monitoring of the influence X-rays have on each specific redox-state with spectroscopic techniques like single-crystal light absorption spectroscopy to determine to which extent you can collect X-ray diffraction data on your crystal before it becomes too heavily influenced/reduced by X- rays.
48 citations
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TL;DR: It is shown that a rapid increase of hydrogen atoms fluctuations at about 220 K, analogous to the one observed in hydrated myoglobin powders, is also observed in a hydrated amino acids mixture with the chemical composition of myoglobin but lacking the polypeptide chain.
Abstract: We give experimental evidence that the main features of protein dynamics revealed by neutron scattering, i.e., the “protein dynamical transition” and the “boson peak”, do not need the protein polypeptide chain. We show that a rapid increase of hydrogen atoms fluctuations at about 220 K, analogous to the one observed in hydrated myoglobin powders, is also observed in a hydrated amino acids mixture with the chemical composition of myoglobin but lacking the polypeptide chain; in agreement with the protein behavior, the transition is abolished in the dry mixture. Further, an excess of low-frequency vibrational modes around 3 meV, typically observed in protein powders, is also observed in our mixture. Our results confirm that the dynamical transition is a water-driven onset and indicate that it mainly involves the amino acid side chains. Taking together the present data and recent results on the dynamics of a protein in denatured conformation and on the activity of dehydrated proteins, it can be concluded that...
47 citations
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TL;DR: A new type of a supramolecular protein polymer which utilizes the original character and reactivity of the monomer protein and can be used for construction of smart nanobiomaterials using various hemoproteins.
Abstract: Artificial self-assembling systems comprised of proteins have the potential not only for mimicking naturally occurring protein clusters but also for creating functionalized supramolecular polymers. Here we report a new type of a supramolecular protein polymer which utilizes the original character and reactivity of the monomer protein. Myoglobin, an oxygen storage hemoprotein, was chosen as the monomer unit and was provided with an externally-attached heme on the protein surface which drives the formation of the fibrous supramolecular assembly through successive interprotein interactions between the external heme and the protein matrix. This assembly governed by myoglobin characteristics shows chemically-responsive stability and can be converted into extremely large protein clustersvia cross-linking. Interestingly, the assembly retains the oxygen storage function. Our present system can be used for construction of smart nanobiomaterials using various hemoproteins.
45 citations
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TL;DR: The results suggest that affinity tags may have effects on protein function and indicate that investigators of affinity-tagged proteins should take this into consideration when investigating the dynamics and other properties of such proteins.
Abstract: Polyhistidine affinity tags are routinely employed as a convenient means of purifying recombinantly expressed proteins. A tacit assumption is commonly made that His tags have little influence on protein structure and function. Attachment of a His tag to the N-terminus of the robust globular protein myoglobin leads to only minor changes to the electrostatic environment of the heme pocket, as evinced by the nearly unchanged Fourier transform infrared spectrum of CO bound to the heme of His-tagged myoglobin. Experiments employing two-dimensional infrared vibrational echo spectroscopy of the heme-bound CO, however, find that significant changes occur to the short time scale (picoseconds) dynamics of myoglobin as a result of His tag incorporation. The His tag mainly reduces the dynamics on the 1.4 ps time scale and also alters protein motions of myoglobin on the slower, >100 ps time scale, as demonstrated by the His tag's influence on the fluctuations of the CO vibrational frequency, which reports on protein structural dynamics. The results suggest that affinity tags may have effects on protein function and indicate that investigators of affinity-tagged proteins should take this into consideration when investigating the dynamics and other properties of such proteins.
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TL;DR: With increasing temperature and incubation time, OxyMb was susceptible to oxidation and conformational changes, whilst MetMb tended to be more stable, thus, the form of myoglobin governed its properties and stability.
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TL;DR: The developmental profiles of zebrafish globins are characterized by means of quantitative real-time reverse transcription PCR to suggest a specific role for each globin, which are also associated with certain events in fish development.
Abstract: Respiratory proteins are responsible for transport and storage of oxygen. It is well established that specific requirements for oxygen during vertebrate ontogeny cause switches of hemoglobin chain expression. Here, we characterize the developmental profiles of zebrafish (Danio rerio) globins by means of quantitative real-time reverse transcription PCR. The total mRNA levels of the hemoglobin chains, including a newly identified embryonic α-chain, as well as myoglobin, neuroglobin, cytoglobin 1 and 2, and globin X were estimated. mRNAs of all globins were detectable in unfertilized eggs, suggesting maternal storage. Embryonic α- and β-hemoglobin mRNA peaked at hatching and the switch to adult hemoglobin expression occurred 16 dpf. Enhanced myoglobin mRNA levels were detected ~31 h post-fertilization (hpf), coinciding with the heart and the muscle development, while neuroglobin mRNA expression pattern correlates with the formation of the nervous system. Amounts of myoglobin and neuroglobin mRNA were similar within an order of magnitude throughout the ontogeny, tentatively supporting a respiratory role of neuroglobin. Cytoglobin 2 mRNA levels increased gradually, whereas cytoglobin 1 mRNA levels increased strongly after ~31 hpf, which is in agreement with a function in cell proliferation. Globin X mRNA level was highest in oocytes, but low in later stages. Together, these data suggest a specific role for each globin, which are also associated with certain events in fish development.
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06 Dec 2011
TL;DR: Oxygen Carriers as Molecular Models of Allosteric Behavior and Properties of Respiratory Proteins are presented.
Abstract: 1 Oxygen Carriers as Molecular Models of Allosteric Behavior.- 1 Introduction and Outline.- 2 Properties of Respiratory Proteins.- 3 Features and Properties of Allosteric Proteins.- 4 Derivation of Oxygen-Saturation Functions: The Generating Function.- 5 Oxygen Binding by Human Hemoglobin.- 6 Oxygen Binding by High Molecular Weight Invertebrate Hemoglobins.- 7 Oxygen Binding by Arthropod Hemocyanins.- 8 Oxygen Binding by Molluscan Hemocyanins.- 9 Concluding Remarks.- References.- 2 Plant Hemoglobins.- 1 Introduction.- 2 Distribution and Physiological Function of Plant Hemoglobins.- 3 Structures and Reactions of Plant Hemoglobins.- 4 Biosynthesis and Degradation of Plant Hemoglobins.- References.- 3 Functions of Cytoplasmic Hemoglobins and Myohemerythrin.- 1 Structure.- 2 Function of Cytoplasmic Hemoglobin and Myohemerythrin at High Concentration: Hemoglobin-Facilitated Oxygen Diffusion.- 3 Functions of Cytoplasmic Hemoglobin at Low Concentration: Myoglobin-Mediated Oxidative Phosphorylation.- 4 Hemoglobin as a Terminal Oxidase.- 5 Hemoglobin-Associated Iron.- 6 Oxygen Storage in Large Domains: The Insect Tracheal Organ.- 7 Oxygen Storage in Very Small Domains.- 8 Nerve Hemoglobins.- 9 Nematode and Trematode Hemoglobins.- 10 Hemoglobin-Mediated Sulfide Utilization.- 11 Summary.- 12 Conclusion.- References.- 4 Structures of Red Blood Cell Hemoglobins.- 1 Introduction.- 2 Invertebrate Hemoglobins.- 3 Vertebrate Hemoglobins.- 4 Conclusions.- References.- 5 Respiratory Function of the Red Blood Cell Hemoglobins of Six Animal Phyla.- 1 Introduction.- 2 RBC Distribution, Hematology, and Morphology.- 3 Respiratory Design.- 4 O2 Binding of RBCs and Purified Hb Components.- 5 Respiratory Functions of RBC Hbs.- 6 Evolution of the RBC.- References.- 6 Molecular Structure/Function Relationships of Hemerythrins.- 1 Introduction.- 2 Structure of the Protein.- 3 Structure of the Diiron Site and O2-Binding Properties.- 4 Allosteric Effectors and Cooperativity in O2 Binding.- 5 Comparisons to O2 Binding in Myoglobin/Hemoglobin and Hemocyanin.- 6 Redox Chemistry of the Diiron Site.- 7 An Unexamined Problem: Protein Folding and Iron Site Assembly.- 8 Relationships to Nonheme Diiron Sites in Other Proteins.- References.- 7 Physiological Function of the Hemerythrins.- 1 Introduction.- 2 Respiratory Design of Hemerythrin-Containing Animals.- 3 In Vitro Respiratory Properties.- 4 In Vivo Respiratory Properties.- 5 Physiological Significance of the Temperature Dependence of the Hemerythrins.- 6 Conclusions.- References.- 8 Molecular Structure of the Extracellular Heme Proteins.- 1 Introduction.- 2 Annelid Extracellular Hemoglobins.- 3 Annelid Extracellular Chlorocruorins.- 4 Pogonophore and Vestimentiferan Extracellular Hemoglobins.- 5 Nematode Extracellular Hemoglobins.- 6 Arthropod Extracellular Hemoglobins.- 7 Molluscan Extracellular Hemoglobins.- 8 Biosynthesis of Invertebrate Hemoglobins.- 9 Conclusions.- References.- 9 Properties and Functions of Extracellular Heme Pigments.- 1 Introduction.- 2 Distribution and Localization.- 3 Oxygen-Binding Properties.- 4 Functions of Extracellular Heme Pigments.- 5 Transport, Transfer, and Storage Functions.- 6 Other Functions.- 7 Summary and Conclusion.- References.- 10 Molluscan Hemocyanins: Structure and Function.- 1 Introduction: The Nature and Distribution of Molluscan Hemocyanins.- 2 Structure of the Native Molluscan Hemocyanin Molecule.- 3 Subunits of Molluscan Hemocyanins.- 4 Primary Structure and Evolution of Molluscan Hemocyanins.- 5 The Active Site and Oxygen Binding.- References.- 11 Respiratory Function of the Molluscan Hemocyanins.- 1 Distribution and Phylogeny of the Molluscan Hemocyanins.- 2 Molecular Size and Structure.- 3 Oxygen-Carrying Capacity of Molluscan Bloods.- 4 Oxygen Equilibrium Properties of Molluscan Hemocyanins.- 5 Physiological Functioning of the Molluscan Hcs.- 6 Summary and Conclusions.- References.- 12 Molecular Structure of the Arthropod Hemocyanins.- 1 Introduction.- 2 The Quaternary Structure.- 3 On the Relationship Between Structure and Function.- 4 Heterogeneity of the Subunits.- 5 Molecular Structure of the Subunit and the Hexamer.- 6 Biosynthesis.- 7 Evolution.- References.- 13 Respiratory Function of Arthropod Hemocyanins.- 1 Introduction.- 2 Hemolymph Oxygen-Binding Properties.- 3 Oxygen Transport: The Functioning of Hemocyanin in Vivo.- 4 Modulation of Hemocyanin O2-Carrying Function.- References.- 14 Structure-Function Relationships of the Ectothermic Vertebrate Hemoglobins.- 1 Introduction.- 2 Hemoglobins of the Agnatha.- 3 Hemoglobin Heterogeneity.- 4 Root Effect Hemoglobins.- 5 Changes in Hemoglobins During Ontogeny.- 6 Methemoglobin.- 7 Summary.- References.- 15 Respiratory Functions of Avian and Mammalian Hemoglobins.- 1 Introduction.- 2 Oxygen Capacity of Blood.- 3 The Affinity of Hemoglobin for Oxygen - Whole Blood.- 4 Cooperativity of Oxygen Binding.- 5 The Bohr Effect in Whole Blood.- 6 Molecular Basis for Differences in Respiratory Properties of Hb.- 7 Modulation of the Respiratory Functions of Hb.- References.
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TL;DR: UV--vis absorption and resonance Raman spectra demonstrate that the first NO molecule binds to the ferrous heme, but while the apoproteins and Cu(I)- or Zn(II)-loaded proteins show characteristic EPR signatures of S = 1/2 six-coordinate heme {FeNO}(7) species that can be observed at liquid nitrogen temperature, the Fe(II-loaded proteins are EPR silent at ≥30 K.
Abstract: Denitrifying NO reductases are evolutionarily related to the superfamily of heme-copper terminal oxidases. These transmembrane protein complexes utilize a heme–nonheme diiron center to reduce two NO molecules to N2O. To understand this reaction, the diiron site has been modeled using sperm whale myoglobin as a scaffold and mutating distal residues Leu-29 and Phe-43 to histidines and Val-68 to a glutamic acid to create a nonheme FeB site. The impact of incorporation of metal ions at this engineered site on the reaction of the ferrous heme with one NO was examined by UV–vis absorption, EPR, resonance Raman, and FTIR spectroscopies. UV–vis absorption and resonance Raman spectra demonstrate that the first NO molecule binds to the ferrous heme, but while the apoproteins and CuI- or ZnII-loaded proteins show characteristic EPR signatures of S = 1/2 six-coordinate heme {FeNO}7 species that can be observed at liquid nitrogen temperature, the FeII-loaded proteins are EPR silent at ≥30 K. Vibrational modes from the...
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TL;DR: Elimination of myoglobin within the body was shown in this study to occur slowly during the period of anuria, and highly efficient myoglobin removal by high cut‐off membrane hemodiafiltration was demonstrated in patients.
Abstract: Acute renal failure is a major complication of rhabdomyolysis. New membranes for hemodialysis have been developed with a high cut-off pore size allowing efficient removal of myoglobin. We report on six patients treated by hemodiafiltration with a high cut-off membrane (HCO-HDF) for myoglobinuric acute renal failure. Rhabdomyolysis was caused by infection in two patients, by a statin in one patient and a non-traumatic crush in another, and followed cardiovascular surgery in two others. Ten HCO-HDF procedures were performed. A high cut-off hemofilter was used, with citrate anticoagulation and postdilutional fluid substitution of 2-3 L/h, dialysate flow 500 mL/min, and blood flow within 250-300 mL/min. Albumin losses were replaced by infusion of human albumin solution, and the mean myoglobin reduction ratio was 77% (range, 62-89%). An excellent clearance of 81 mL/min (range 42-131 mL/min) was achieved. Nearly 5 g of myoglobin was removed into the dialysate collected in one of the procedures. A high rebound in serum myoglobin, on average to 244% of the post-procedure myoglobin level, was observed. The four patients alive at the time remained anuric for a week. Slow myoglobin elimination with a mean half-time of 39 h (range 19-59 h) was observed in that period. Highly efficient myoglobin removal by high cut-off membrane hemodiafiltration was demonstrated in our patients. Rapid redistribution from the extracellular fluid and sustained myoglobin release were suggested by the high rebound observed. Elimination of myoglobin within the body was shown in our study to occur slowly during the period of anuria.
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TL;DR: A novel, S-nitrosation-dependent allosteric mechanism in this low-affinity Mb that may contribute to targeted O₂-linked SNO release in the hypoxic fish heart and be of importance in preserving cardiac function during intense exercise is revealed.
Abstract: Myoglobin (Mb) serves in the facilitated diffusion and storage of O2 in heart and skeletal muscle, where it also regulates O2 consumption via nitric oxide (NO) scavenging or generation. S-nitrosati...
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TL;DR: Based on model simulations, the contribution of myoglobin oxygenation to the total NIRS signal can be significantly different under pathophysiological conditions, such as diabetes and peripheral arterial disorder.
Abstract: The quantitative contributions of hemoglobin and myoglobin oxygenation in skeletal muscle depend on physiological factors, especially muscle blood flow (Q m ) and capillary permeability-surface area (PS). Near-infrared spectroscopy (NIRS) can be used to quantify total heme oxidation, but it is unable to distinguish between hemoglobin and myoglobin. Therefore, a mechanistic computational model has been developed to distinguish the contributions of oxygenated hemoglobin and myoglobin to the total NIRS signal. Model simulations predict how Q m and PS can affect oxygenated hemoglobin and myoglobin.Although both hemoglobin and myoglobin oxygenation decrease with impaired Q m , simulations show that myoglobin provides a greater contribution to the overall NIRS signal. A decrease of PS primarily affects myoglobin oxygenation. Based on model simulations, the contribution of myoglobin oxygenation to the total NIRS signal can be significantly different under pathophysiological conditions, such as diabetes and peripheral arterial disorder.
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TL;DR: The study shows the unique nature of these common pentose sugars in spontaneous glycation reactions with proteins, and the modification is likely due to an internal cross-link formed during a glycation reaction involving the N-terminus and an internal amine group.
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TL;DR: Structural modifications of metmyoglobin after short-term and long-term glycation by fructose appeared to modify Arg139 to arg-pyrimidine, which exhibited antioxidative activity and might be involved in the conversion of met (Fe3+) to oxy (Fe2+) form of myoglobin.
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TL;DR: The present study crystallized human Cgb in the presence of a reductant Na2S2O4 under a carbon monoxide (CO) atmosphere, and determined the crystal structure at 2.6 Å resolution, providing the structural basis for further discussion of the unique ligand‐binding properties of Cgb.
Abstract: Cytoglobin (Cgb) is a vertebrate heme-containing globin-protein expressed in a broad range of mammalian tissues. Unlike myoglobin, Cgb displays a hexa-coordinated (bis-hystidyl) heme iron atom, having the heme distal His81(E7) residue as the endogenous sixth ligand. In the present study, we crystallized human Cgb in the presence of a reductant Na₂S₂O₄ under a carbon monoxide (CO) atmosphere, and determined the crystal structure at 2.6 A resolution. The CO ligand occupies the sixth axial position of the heme ferrous iron. Eventually, the imidazole group of His81(E7) is expelled from the sixth position and swings out of the distal heme pocket. The flipping motion of the His81 imidazole group accompanies structural readjustments of some residues (Gln62, Phe63, Gln72, and Ser75) in both the CD-corner and D-helix regions of Cgb. On the other hand, no significant structural changes were observed in other Cgb regions, for example, on the proximal side. These structural alterations that occurred as a result of exogenous ligand (CO) binding are clearly different from those observed in other vertebrate hexa-coordinated globins (mouse neuroglobin, Drosophila melanogaster hemoglobin) and penta-coordinated sperm whale myoglobin. The present study provides the structural basis for further discussion of the unique ligand-binding properties of Cgb.
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TL;DR: A truncated hemoglobin of microbial origin (Thermobifida fusca) investigated in the present work, displays the specific spectroscopic signature of a peroxidase, in agreement with the presence of strong H-bonding residues, i.e., tyrosine and tryptophan, within the distal pocket.
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TL;DR: In this article, the thermal denaturation of ovalbumin, lysozyme, myoglobin and fibrinogen at different BTS concentrations were investigated using differential scanning calorimetry (DSC) and circular dichroism (CD) spectroscopy.
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15 Dec 2011TL;DR: A review of the chemistry of iron porphyrins, from Fe(0) to Fe(V) can be found in this paper, where the authors discuss the properties, reactions, uses and biological relevance of natural iron Porphyrin (hemes) and their synthetic analogs.
Abstract: This article reviews most aspects of the chemistry of iron porphyrins, from Fe(0) to Fe(V), including occurrence and roles of natural iron porphyrins (hemes) and their synthetic analogs, structures and electron configurations of iron porphyrins of all oxidation and spin states, π electron configuration of the porphyrin ring, synthesis of metal-free porphyrins and other related macrocycles, insertion of iron into free-base porphyrins and related macrocycles, the properties, reactions, uses and biological relevance of iron(0), -(I), -(II) porphyrins (the latter with S = 0, 1, and 2 spin state possibilities), of iron(II) porphyrin π-cation radicals, of iron(III) porphyrins (with S = 1/2, 3/2, and 5/2 spin state possibilities), of iron(III) porphyrin and corrole π-cation radicals, of iron(IV) porphyrins (including five- and six-coordinate ferryl (FeO)2+, iron(IV) phenyl, carbene and hydrazine complexes, and the bis-methoxide complex) and a comparison of iron(IV) porphyrins to iron(III) porphyrin π-cation radicals, of iron(IV) porphyrin π-cation radicals, and of the possible existence of iron(V) porphyrins. Included in the Fe(II) part are sections on addition of ligands to four-coordinate iron(II) porphyrins, including equilibrium binding constants, photodissociation of ligands from PFeL2 complexes, binding of small molecules (O2, CO, NO, HNO) to 5-coordinate iron(II) porphyrins and design of porphyrin ligands that will mimic the active sites of heme proteins such as myoglobin and hemoglobin, the cytochromes P450 and nitric oxide synthases, and the nitrophorins and guanylyl cyclases. Included in the iron(III) part are sections on both 5- and 6-coordinate high-spin complexes and their similarities and differences, bridged or through-space magnetically coupled complexes of high-spin iron(III) porphyrins with other metal complexes as possible models for cytochrome oxidase and the assimilatory sulfite reductases, coupled oxidation of hemes by hydrogen peroxide or its equivalent, and the relationship of this reactivity to the reactions of heme oxygenase, iron(III) porphyrins as reduction catalysts, and photochemistry of iron(III) porphyrins, possible electron configurations of low-spin iron(III) porphyrins, the phenomenon and possible electronic consequences of ruffling of the porphinato core in iron(III) porphyrins, the preferred orientation of planar axial ligands bound to low-spin iron(III) porphyrins, NO complexes of iron(III) porphyrins, reduction potentials, equilibrium constants and rates of axial-ligand addition and exchange, kinetics of axial-ligand rotation and porphyrin ring inversion, kinetics of reduction and autoreduction of iron(III) porphyrins, electron self-exchange between low-spin iron(III) and iron(II) porphyrins, synthetic ferriheme proteins, and synthesis of five-coordinate low-spin iron(III) porphyrins having σ-alkyl or σ-aryl groups as axial ligands. The iron(IV) and iron(IV) cation radical sections discuss the high-valent states of cytochromes P450 and related enzymes.
Keywords:
heme;
synthesis, axial ligand;
coordination number;
d electron configuration;
π-electron configuration;
high-spin;
low-spin;
hemoglobin;
cytochrome;
P450;
electron transfer
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TL;DR: A mid-IR study of the configuration and ultrafast dynamics of CO in the distal heme pocket site of the sensor PAS domain FixLH, employing a recently developed method that provides a unique combination of high spectral resolution and range and high sensitivity.
Abstract: In heme-based sensor proteins, ligand binding to heme in a sensor domain induces conformational changes that eventually lead to changes in enzymatic activity of an associated catalytic domain. The bacterial oxygen sensor FixL is the best-studied example of these proteins and displays marked differences in dynamic behavior with respect to model globin proteins. We report a mid-IR study of the configuration and ultrafast dynamics of CO in the distal heme pocket site of the sensor PAS domain FixLH, employing a recently developed method that provides a unique combination of high spectral resolution and range and high sensitivity. Anisotropy measurements indicate that CO rotates toward the heme plane upon dissociation, as is the case in globins. Remarkably, CO bound to the heme iron is tilted by ∼30° with respect to the heme normal, which contrasts to the situation in myoglobin and in present FixLH–CO X-ray crystal structure models. This implies protein-environment-induced strain on the ligand, which is possib...
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TL;DR: A functional model of NOR is engineered by creating a two His and one Glu non‐heme iron center in sperm whale myoglobin that adopts a low‐spin state with bis‐His coordination in the absence of metal ions binding to the designed metal center.
Abstract: Rational design of functional enzymes is a powerful strategy to gain deep insights into more complex native enzymes, such as nitric oxide reductase (NOR). Recently, we engineered a functional model of NOR by creating a two His and one Glu (2-His-1-Glu) non-heme iron center in sperm whale myoglobin (swMb L29E, F43H, H64, called FeBMb(-His)). It was found that FeBMb(-His) adopts a low-spin state with bis-His coordination in the absence of metal ions binding to the designed metal center. However, no structural information was available for the variant in this special spin state. We herein performed molecular modeling of FeBMb(-His) and compared with the X-ray structure of its copper bound derivative, Cu(II)-CN−-FeBMb(-His), resolved recently at a high resolution (1.65 A) (PDB entry 3MN0). The simulated structure shows that mutation of Leu to Glu at position 29 in the hydrophobic heme pocket alters the folding behavior of Mb. The hydrogen bond between Glu29 and His64 further plays a role in stabilizing the bis-His (His64/His93) coordination structure. This study offers an excellent example of using molecular modeling to gain insights in rational design of both structural and functional proteins. Proteins 2011. © 2010 Wiley-Liss, Inc.
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TL;DR: The systematic analysis of the amide VI band of the polypeptides and the proteins allowed correlating the signal appearing at ∼525 cm −1 to α-helical structures and signals at ∼545 cm-1 to β-sheet contributions.
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20 Apr 2011
TL;DR: In this article, the authors present a comparison of matter and methods for making, storing and administering artificial blood substitutes, including nanoparticles, polymers and/or polymersomes comprising of poly(ethylene oxide)-block-poly(e-caprolactone) (PEO-b-PCL).
Abstract: Compositions of matter and methods for making, storing and administering artificial blood substitutes. Artificial blood substitutes may have oxygen carriers that encapsulate an oxygen-binding compound in a polymer vesicle. Oxygen-binding compounds may include hemoglobin, myoglobin, or other oxygen binding compounds having characteristics similar to hemoglobin. Oxygen carriers may include nanoparticles, polymers and/or polymersomes comprising of poly(ethylene oxide)-block-poly(e-caprolactone) (PEO-b-PCL) and related diblock copolymers of poly(ethylene oxide)-block-poly(γ-methyl e-caprolactone) (PEO-b-PMCL). The oxygen carriers may have tunable oxygen-binding capacities, uniform and appropriately small size distributions, and human bloodlike viscosities and oncotic properties.
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TL;DR: The complete amino acid sequence of turkey myoglobin was determined and compared with that of poultry and red meat myoglobins and it was found that Proximal (position 93) and distal (position 64) histidine residues, responsible for maintaining the stability of haeme, are conserved in Turkey myoglobin.
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TL;DR: This study has successfully generated and spectroscopically characterized the H93G Mb cavity mutant ligated with less common alkylamine ligands (models for Lys or the amine group of N-terminal amino acids) in numerous heme iron states, the first systematic spectral study of models for alkyamine- or terminal amine-ligated heme centers in proteins.
Abstract: His93Gly sperm whale myoglobin (H93G Mb) has the proximal histidine ligand removed to create a cavity for exogenous ligand binding, providing a remarkably versatile template for the preparation of model heme complexes The investigation of model heme adducts is an important way to probe the relationship between coordination structure and catalytic function in heme enzymes In this study, we have successfully generated and spectroscopically characterized the H93G Mb cavity mutant ligated with less common alkylamine ligands (models for Lys or the amine group of N-terminal amino acids) in numerous heme iron states All complexes have been characterized by electronic absorption and magnetic circular dichroism spectroscopy in comparison with data for parallel imidazole-ligated H93G heme iron moieties This is the first systematic spectral study of models for alkylamine- or terminal amine-ligated heme centers in proteins High-spin mono- and low-spin bis-amine-ligated ferrous and ferric H93G Mb adducts have been prepared together with mixed-ligand ferric heme complexes with alkylamine trans to nitrite or imidazole as heme coordination models for cytochrome c nitrite reductase or cytochrome f, respectively Six-coordinate ferrous H93G Mb derivatives with CO, NO, and O(2) trans to the alkylamine have also been successfully formed, the latter for the first time Finally, a novel high-valent ferryl species has been generated The data in this study represent the first thorough investigation of the spectroscopic properties of alkylamine-ligated heme iron systems as models for naturally occurring heme proteins ligated by Lys or terminal amines