Showing papers on "Myoglobin published in 2014"
TL;DR: It is shown that metallo-substituted myoglobins constitute viable CH amination catalysts, revealing a distinctive reactivity trend as compared to synthetic metalloporphyrin counterparts.
105 citations
TL;DR: This work shows for the first time that cobalt myoglobin (CoMyo) catalyzes hydrogen production in mild aerobic conditions with turnover number of 520 over 8 hours and demonstrates that protein scaffolds can augment and modulate the intrinsic catalytic activity of molecular hydrogen production catalysts.
70 citations
TL;DR: Force data suggest that the HydroMIPs have produced selective cavities for the template protein in the MIPs and the extent of non-specific protein binding on, for example, a non-imprinted polymer (NIP) control surface is quantified.
Abstract: Hydrogel-based molecularly imprinted polymers (HydroMIPs) were prepared for several proteins (haemoglobin, myoglobin and catalase) using a family of acrylamide-based monomers. Protein affinity towards the HydroMIPs was investigated under equilibrium conditions and over a range of concentrations using specific binding with Hill slope saturation profiles. We report HydroMIP binding affinities, in terms of equilibrium dissociation constants (Kd) within the micro-molar range (25 ± 4 μM, 44 ± 3 μM, 17 ± 2 μM for haemoglobin, myoglobin and catalase respectively within a polyacrylamide-based MIP). The extent of non-specific binding or cross-selectivity for non-target proteins has also been assessed. It is concluded that both selectivity and affinity for both cognate and non-cognate proteins towards the MIPs were dependent on the concentration and the complementarity of their structures and size. This is tentatively attributed to the formation of protein complexes during both the polymerisation and rebinding stages at high protein concentrations. We have used atomic force spectroscopy to characterize molecular interactions in the MIP cavities using protein-modified AFM tips. Attractive and repulsive force curves were obtained for the MIP and NIP (non-imprinted polymer) surfaces (under protein loaded or unloaded states). Our force data suggest that we have produced selective cavities for the template protein in the MIPs and we have been able to quantify the extent of non-specific protein binding on, for example, a non-imprinted polymer (NIP) control surface.
57 citations
TL;DR: The active site of myoglobin compound II over the pH range of 3.9–9.5 is probed, providing insight into Nature’s ability to tune catalytic function through its choice of axial ligand.
Abstract: To provide insight into the iron(IV)hydroxide pKa of histidine ligated heme proteins, we have probed the active site of myoglobin compound II over the pH range of 3.9–9.5, using EXAFS, Mossbauer, and resonance Raman spectroscopies. We find no indication of ferryl protonation over this pH range, allowing us to set an upper limit of 2.7 on the iron(IV)hydroxide pKa in myoglobin. Together with the recent determination of an iron(IV)hydroxide pKa ∼ 12 in the thiolate-ligated heme enzyme cytochrome P450, this result provides insight into Nature’s ability to tune catalytic function through its choice of axial ligand.
50 citations
TL;DR: This work elucidate and solve a long-standing problem related to the quantum-mechanical description of the respiration process, namely that DFT calculations predict a strong imbalance between O2 and CO binding, favoring the latter to an unphysically large extent.
Abstract: We carry out a first-principles atomistic study of the electronic mechanisms of ligand binding and discrimination in the myoglobin protein. Electronic correlation effects are taken into account using one of the most advanced methods currently available, namely a linear-scaling density functional theory (DFT) approach wherein the treatment of localized iron 3d electrons is further refined using dynamical mean-field theory. This combination of methods explicitly accounts for dynamical and multireference quantum physics, such as valence and spin fluctuations, of the 3d electrons, while treating a significant proportion of the protein (more than 1,000 atoms) with DFT. The computed electronic structure of the myoglobin complexes and the nature of the Fe–O2 bonding are validated against experimental spectroscopic observables. We elucidate and solve a long-standing problem related to the quantum-mechanical description of the respiration process, namely that DFT calculations predict a strong imbalance between O2 and CO binding, favoring the latter to an unphysically large extent. We show that the explicit inclusion of the many-body effects induced by the Hund’s coupling mechanism results in the correct prediction of similar binding energies for oxy- and carbonmonoxymyoglobin.
41 citations
TL;DR: The binding of the phenazinium dye janus green blue to two heme proteins, hemoglobin and myoglobin, was studied by biophysical and microcalorimetry techniques and the involvement of ionic interactions in the complexation was confirmed.
Abstract: The binding of the phenazinium dye janus green blue (JGB) to two heme proteins, hemoglobin (Hb) and myoglobin (Mb), was studied by biophysical and microcalorimetry techniques. Ground state complex formation was ascertained from absorbance and fluorescence data. The binding affinity of JGB to myoglobin was higher than that to hemoglobin. The dye induced conformational changes in the proteins as revealed from circular dichroism, synchronous fluorescence and 3D fluorescence results. The binding was characterized in calorimetry by endothermic heats. The negative standard molar Gibbs energy in both cases suggested the spontaneity of the reaction. The positive enthalpy and positive entropy changes characterized the binding of the dye to the proteins. The higher affinity to Mb (K = 8.21 × 104 M−1) over Hb (K = 6.60 × 104 M−1) was confirmed from calorimetry results. The binding involved contribution from both polyelectrolytic and non-polyelectrolytic forces. pH dependent studies confirmed the involvement of ionic interactions in the complexation. The molecular details of the interaction in terms of structural aspects and energetics are described.
40 citations
01 Jan 2014
TL;DR: Meat industry exploits packaging and antioxidant strategies to manipulate myoglobin chemistry and thus improve the meat color.
Abstract: Color is an important quality trait influencing consumers' meat purchase decisions Myoglobin is the sarcoplasmic heme protein primarily responsible for the color of meat The biochemistry of globin chain, redox state of heme iron, and the ligand bound to the sixth coordinate of heme iron govern the color of raw, cooked, and cured meats Furthermore, the amino acid sequence of myoglobin influences its interactions with small biomolecules and biochemical attributes such as autoxidation, heme retention, thermostability, and oxygen affinity Meat industry exploits packaging and antioxidant strategies to manipulate myoglobin chemistry and thus improve the meat color
38 citations
TL;DR: Fluorescence studies suggested that the complexes formed between hydroxylated single-walled carbon nanotubes and hemoglobin/myoglobin by hydrogen bonding, hydrophobic, and π-π stacking interactions well supported the experimental results.
Abstract: Herein, we studied the binding interactions between hydroxylated single-walled carbon nanotubes and hemoglobin and myoglobin by the use of multi-spectral techniques and molecular modeling. The ultraviolet-vis absorbance and circular dichroism spectral results indicated that the binding interactions existed between hydroxylated single-walled carbon nanotubes and hemoglobin/myoglobin. These binding interactions partially affected the soret/heme bands of hemoglobin and myoglobin. The secondary structures of hemoproteins were partially destroyed by hydroxylated single-walled carbon nanotubes. Fluorescence studies suggested that the complexes formed between hydroxylated single-walled carbon nanotubes and hemoglobin/myoglobin by hydrogen bonding, hydrophobic, and π-π stacking interactions. In addition, molecular modeling analysis well supported the experimental results.
37 citations
TL;DR: The first-order radiative rate constant for (1)O2 deactivation within the protein was found to be 8.1 ± 1.3 times larger than the one in aqueous solutions, indicating the strong influence of the protein matrix on the radiative ( 1)O1 deactivation.
Abstract: A nanosecond laser near-infrared spectrometer was used to study singlet oxygen ((1)O2) emission in a protein matrix. Myoglobin in which the intact heme is substituted by Zn-protoporphyrin IX (ZnPP) was employed. Every collision of ground state molecular oxygen with ZnPP in the excited triplet state results in (1)O2 generation within the protein matrix. The quantum yield of (1)O2 generation was found to be equal to 0.9 ± 0.1. On the average, six from every 10 (1)O2 molecules succeed in escaping from the protein matrix into the solvent. A kinetic model for (1)O2 generation within the protein matrix and for a subsequent (1)O2 deactivation was introduced and discussed. Rate constants for radiative and nonradiative (1)O2 deactivation within the protein were determined. The first-order radiative rate constant for (1)O2 deactivation within the protein was found to be 8.1 ± 1.3 times larger than the one in aqueous solutions, indicating the strong influence of the protein matrix on the radiative (1)O2 deactivation. Collisions of singlet oxygen with each protein amino acid and ZnPP were assumed to contribute independently to the observed radiative as well as nonradiative rate constants.
35 citations
TL;DR: Glyoxal increases the thermal stability of hemoglobin, while it decreases the stability of myoglobin, and the same oxoaldehyde exerts different effects on hemoglobin and myoglobin and may be associated with different structural properties of the proteins.
34 citations
TL;DR: In the case of Parma ham, a continuing increase in concentration of glycerol, choline, and free amino acids, as followed for 15 months by high resolution 1H NMR of ham extracts, indicates activity of lipolytic and proteolytic enzymes as discussed by the authors.
TL;DR: Interactions of heme side chains, especially 2,4-vinyls and 6,7-propionates, with globin, as well as the electronic coupling of the heme bands with those of intrinsic protein chromophores, contribute to the appearance of the prominent positive Soret CD band of Mb and Hb.
TL;DR: The BMIBF4 significantly destabilizes the myoglobin structure while the EMIAc does not, likely due to differences in anion interaction capabilities, and may be used as a supplement in protein folding experiments, potentially allowing access to proteins which have been traditionally difficult to denature.
Abstract: The use of ionic liquids in biochemical and biophysical applications has increased dramatically in recent years due to their interesting properties. We report results of a thermodynamic characterization of the chaotrope-induced denaturation of equine myoglobin in two different ionic liquid aqueous environments using a combined absorption/fluorescence spectroscopic approach. Denaturation by guanidinium hydrochloride was monitored by loss of heme absorptivity and limited unfolding structural information was obtained from Forster resonance energy transfer experiments. Results show that myoglobin unfolding is generally unchanged in the presence of ethylmethylimidazolium acetate (EMIAc) in aqueous solution up to 150 mM concentration but is facilitated by butylmethylimidazolium boron tetrafluoride (BMIBF4) in solution. The presence of 150 mM BMIBF4 alone does not induce unfolding but destabilizes the structure as observed by a decrease in threshold denaturant concentration for unfolding and an 80% decrease in t...
TL;DR: The trends reflected from the reactivity of each lysine as a function of acetonitrile denaturation in the present study support that PARP-C exists as a monomer in solution with a close-packed C-terminal α helix.
Abstract: Ultraviolet photodissocation (UVPD) mass spectrometry was used for high mass accuracy top-down characterization of two proteins labeled by the chemical probe, S-ethylacetimidate (SETA), in order to evaluate conformational changes as a function of denaturation. The SETA labeling/UVPD-MS methodology was used to monitor the mild denaturation of horse heart myoglobin by acetonitrile, and the results showed good agreement with known acetonitrile and acid unfolding pathways of myoglobin. UVPD outperformed electron transfer dissociation (ETD) in terms of sequence coverage, allowing the SETA reactivity of greater number of lysine amines to be monitored and thus providing a more detailed map of myoglobin. This strategy was applied to the third zinc-finger binding domain, domain C, of PARP-1 (PARP-C), to evaluate the discrepancies between the NMR and crystal structures which reported monomer and dimer forms of the protein, respectively. The trends reflected from the reactivity of each lysine as a function of aceton...
TL;DR: A general linear response theory is formulated to describe time-dependent and -independent protein conformational changes upon CO binding with myoglobin and the newly formulated theory describes the mechanical propagation following ligand-binding as a function of time, space and types of the perturbation forces.
TL;DR: Mass spectrometric investigations revealed that although cherry-red carboxymyoglobin is more stable than oxymyoglobin, both redox forms undergo lipid oxidation-induced oxidation in model systems, and the unique biochemistry of turkey myoglobin could be responsible for its greater thermostability in model system as well as the pink color defect observed in fully cooked uncured turkey products.
Abstract: Meat color is the most important quality trait influencing consumer purchase decisions. The interinfluential interactions between myoglobin and biomolecules govern color stability in meat. The advances in proteomics, such as high throughput analytical tools in mass spectrometry, 2-dimensional electrophoresis, and bioinformatics, offer themselves as robust techniques to characterize the proteome basis of muscle- and species-specific meat color phenomena. Differential abundance of chaperones and antioxidant proteins contributes to muscle-specific color stability in beef; the greater abundance of chaperones and antioxidant proteins in color-stable Longissimus lumborum than in color-labile Psoas major protects myoglobin and contributes to superior color stability of beef Longissimus steaks. Lipid oxidation-induced myoglobin oxidation is more critical to beef color than pork color due to the inherent differences in myoglobin chemistry; the number of nucleophilic histidine residues adducted by reactive aldehydes is greater in beef myoglobin than in pork myoglobin. Preferential adduction of secondary products of lipid oxidation to beef myoglobin accelerates metmyoglobin formation at a greater degree than in its pork counterpart. Mass spectrometric investigations revealed that although cherry-red carboxymyoglobin is more stable than oxymyoglobin, both redox forms undergo lipid oxidation-induced oxidation in model systems. The accuracy of mass spectrometry to detect the molecular mass of proteins has been applied to differentiate myoglobins from closely related meat animals, such as goats and sheep or emu and ostrich. In addition, this approach indicated that turkey myoglobin is 350 Da greater in molecular mass than beef myoglobin, and the unique biochemistry of turkey myoglobin could be responsible for its greater thermostability in model systems as well as the pink color defect observed in fully cooked uncured turkey products.
TL;DR: This study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation, which requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels.
Abstract: The systemic response to decreasing oxygen levels is hypoxic vasodilation. While this mechanism has been known for more than a century, the underlying cellular events have remained incompletely understood. Nitrite signaling is critically involved in vessel relaxation under hypoxia. This can be attributed to the presence of myoglobin in the vessel wall together with other potential nitrite reductases, which generate nitric oxide, one of the most potent vasodilatory signaling molecules. Questions remain relating to the precise concentration of nitrite and the exact dose-response relations between nitrite and myoglobin under hypoxia. It is furthermore unclear whether regulatory mechanisms exist which balance this interaction. Nitrite tissue levels were similar across all species investigated. We then investigated the exact fractional myoglobin desaturation in an ex vivo approach when gassing with 1% oxygen. Within a short time frame myoglobin desaturated to 58±12%. Given that myoglobin significantly contributes to nitrite reduction under hypoxia, dose-response experiments using physiological to pharmacological nitrite concentrations were conducted. Along all concentrations, abrogation of myoglobin in mice impaired vasodilation. As reactive oxygen species may counteract the vasodilatory response, we used superoxide dismutase and its mimic tempol as well as catalase and ebselen to reduce the levels of reactive oxygen species during hypoxic vasodilation. Incubation of tempol in conjunction with catalase alone and catalase/ebselen increased the vasodilatory response to nitrite. Our study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation. This requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels. Reactive oxygen species, in turn, modulate this vasodilation response.
TL;DR: A kinetic model is established for the entire cycle of the protein transition in a wide time range from 100 ps to 10 ms and attributes the biphasic kinetics to the involvement of two conformational substates of the first intermediate, which are generated by the interplay between the distal histidine and the photodissociated CO.
Abstract: Conformational substates of proteins are generally considered to play important roles in regulating protein functions, but an understanding of how they influence the structural dynamics and functions of the proteins has been elusive. Here, we investigate the structural dynamics of sperm whale myoglobin associated with the conformational substates using picosecond X-ray solution scattering. By applying kinetic analysis considering all of the plausible candidate models, we establish a kinetic model for the entire cycle of the protein transition in a wide time range from 100 ps to 10 ms. Four structurally distinct intermediates are formed during the cycle, and most importantly, the transition from the first intermediate to the second one (B → C) occurs biphasically. We attribute the biphasic kinetics to the involvement of two conformational substates of the first intermediate, which are generated by the interplay between the distal histidine and the photodissociated CO.
TL;DR: Electrochemical impedance studies of the bioelectrode showed significant changes in charge transfer resistance (Ret), predominantly in the low AC frequency region of <40 Hz, on immunoreaction with human cardiac myoglobin antigen (Ag-cMb).
Abstract: We report the covalent immobilization of three-dimensional carboxyl-functionalized Pt(MPA) nanoparticles with myoglobin protein antibody by carbodiimide coupling reaction deposited onto an indium-tin-oxide-coated glass plate for the construction of a bioelectrode. This bioelectrode assembly was characterized by spectro/microscopic and electrochemical techniques. Electrochemical impedance studies of the bioelectrode showed significant changes in charge transfer resistance (Ret), predominantly in the low AC frequency region of <40 Hz, on immunoreaction with human cardiac myoglobin antigen (Ag-cMb). Ag-cMb detection in phosphate buffer exhibited a linear range of 0.01 μg mL−1 to 1 μg mL−1 with a sensitivity of 184.8 Ω cm2 per decade.
TL;DR: It is demonstrated that recombinant coiled-coil silk proteins provide a safe and environmentally friendly alternative to sol-gels for stabilizing heme proteins for use as optical biosensors.
TL;DR: An investigation of the hydration dependence of myoglobin dynamics and the relevance of protein+hydration water relaxations and of the thermodynamic state of hydration water to the onset of the protein dynamical transition is discussed.
TL;DR: Interestingly, for the first time, ILs having acetate and bromide anions were proven to counteract the cold-induced unfolding of proteins.
Abstract: Significant non-reversible two-state denaturation was observed for proteins such as myoglobin (Mb) and α-chymotrypsin (CT) with decreasing temperature in the presence of 1-butyl-3-methylimidazolium-based ([C4mim]+X−) ionic liquids (ILs) with various anions (X−) Interestingly, for the first time, ILs having acetate and bromide anions were proven to counteract the cold-induced unfolding of proteins
TL;DR: The singular value decomposition analysis of the experimental data suggests that two structurally distinguishable intermediates are formed within 100 ps, and the global structural change occurring on the time scale of 70 ps is identified.
TL;DR: Results indicate that the identified peptides can be used for the detection of myoglobin and may be a cost effective alternative to antibodies.
TL;DR: A link between lipid supplementation and increased Mb in skeletal muscle is shown and addition of antioxidant prevented Mb increases in lipid-supplemented normoxic cells and mitigated Mb increases under hypoxia, suggesting a pathway for Mb regulation through redox signaling independent of CN.
Abstract: Myoglobin (Mb) is an oxygen-binding muscular hemeprotein regulated via Ca2+-signaling pathways involving calcineurin (CN), with Mb increases attributed to hypoxia, exercise, and nitric oxide. Here,...
TL;DR: It was shown that without any significant loss in the adsorption capacity, MGb-MIP cryogels can be used a number of times for myoglobin recognition and separation.
Abstract: Myoglobin is a primary iron, and oxygen-binding protein of muscle tissues and levels can be an important diagnostic biomarker for acute myocardial infarction, myocardial necrosis, or other cardiac diseases. The establishment of myoglobin recognition systems is important because of its protein's structural and functional values in physiology, biochemistry, and diagnostic value in some damaged muscle tissue and cardiac diseases. For this purpose, we used molecular imprinting technique for myoglobin recognition from aqueous solutions and human plasma. In the first step, myoglobin-imprinted poly(hydroxyethyl methacrylate) (PHEMA) cryogels (MGb-MIP) were prepared, and optimum myoglobin adsorption conditions were determined. Selectivity experiments have been done with the competitive proteins, and myoglobin adsorption from IgG and albumin-free human plasma was studied. The purity of the desorbed samples was determined with SDS-PAGE. The desorption efficiency and reusability of the MGb-MIP cryogels were tested, and it was shown that without any significant loss in the adsorption capacity, MGb-MIP cryogels can be used a number of times for myoglobin recognition and separation.
TL;DR: The results of the present study indicate that the effects of lactate on myoglobin are temperature and pH dependent and suggests that the color stability of lactATE-enhanced fresh meat is not due to direct interactions between the ingredient and the heme protein.
30 Jun 2014
TL;DR: The current data concerning connection of heme and peroxidation were summarized and analysed and hypothesis can be put forward that loss of cellular antioxidants might precede the rise of peroxidase-like activity, thus being a sign of incipient discoloration of meats and muscle components of foods.
Abstract: It is known, that lipid peroxidation is one of the main factors limiting the quality and acceptability of meat and other animal tissues. The current data concerning connection of heme and peroxidation were summarized and analysed here. The muscle food compounds that are most influenced by oxidative processes include unsaturated fatty acids of lipids, amino acids of proteins and heme groups of pigments. Heme proteins and particularly myoglobin are abundant in muscle tissues. Meat colour is primarily influenced by the concentration and chemical State of heme pigments, myoglobin and hemoglobin. Oxygenated myoglobin oxidized to the brown metmyoglobin form and its accumulation is highly correlated with progress of lipid peroxidation. Heme proteins such as hemoglobin or myoglobin accelerate the decomposition of hydroperoxides to free radicals. Metmyoglobin possesses «pseudoperoxidase» activity and catalyzes the oxidation of various compounds following the reaction with hydrogen peroxide. The reaction between hydrogen peroxide and metmyoglobin results in the formation of two active hypervalent myoglobin species, perferrylmyoglobin (·MbFe(IV)=0) and ferrylmyoglobin (MbFe(IV)=0), which participate in lipid oxidation catalysis. Both MbFe(IV)=0 and ·MbFe(IV)=0 are deactivated in the presence of reducing agents, whose nature determines the overall effect of the pseudoperoxidase cycle. Hypothesis can be put forward that loss of cellular antioxidants might precede the rise of peroxidase-like activity, thus being a sign of incipient discoloration of meats and muscle components of foods.
TL;DR: Thiocyanate and selenocyanates can be good local probes of local electrostatic environment in the heme pocket, and the vibrational lifetimes determined for MbNCS and MbNCSe are still fairly long compared to those of azide and cyanide myoglobin systems studied before.
Abstract: The structure and vibrational dynamics of SCN- and SeCN-bound myoglobin have been investigated using polarization-controlled IR pump-probe measurements and quantum chemistry calculations. The complexes are found to be in low and high spin states, with the dominant contribution from the latter. In addition, the Mb:SCN high spin complex exhibits a doublet feature in the thiocyanate stretch IR absorption spectra, indicating two distinct molecular conformations around the heme pocket. The binding mode of the high spin complexes was assigned to occur through the nitrogen atom, contrary to the binding through the sulfur atom that was observed in myoglobin derived from Aplysia Limacina. The vibrational energy relaxation process has been found to occur substantially faster than those of free SCN− and SeCN− ions and neutral SCN- and SeCN-derivatized molecules reported previously. This supports the N-bound configurations of MbNCS and MbNCSe, because S- and Se-bound configurations are expected to have significantly long lifetimes due to the insulation effect by heavy bridge atom like S and Se in such IR probes. Nonetheless, even though their lifetimes are much shorter than those of corresponding free ions in water, the vibrational lifetimes determined for MbNCS and MbNCSe are still fairly long compared to those of azide and cyanide myoglobin systems studied before. Thus, thiocyanate and selenocyanate can be good local probes of local electrostatic environment in the heme pocket. The globin dependence on binding mode and vibrational dynamics is also discussed.
TL;DR: Using THz time-scale spectroscopy to conduct an initial set of studies on myoglobin, it is determined that the perturbation from the heme-ligand complex has a strong influence on the characteristics of the myoglobin collective dynamics that are excited upon binding.
Abstract: In this investigation we use THz time-scale spectroscopy to conduct an initial set of studies on myoglobin with the aim of providing further insight into the global, collective thermal fluctuations in the protein that have been hypothesized to play a prominent role in the dynamic formation of transient ligand channels as well as in shaping the molecular level basis for ligand discrimination. Using the two ligands O2 and CO, we have determined that the perturbation from the heme–ligand complex has a strong influence on the characteristics of the myoglobin collective dynamics that are excited upon binding. Further, the differences detected in the collective protein motions in Mb–O2 compared with those in Mb–CO appear to be intimately tied with the pathways of long-range allosteric communication in the protein, which ultimately determine the trajectories selected by the respective ligands on the path to and from the heme-binding cavity.