Showing papers on "Myoglobin published in 2009"

The New Chemical Biology of Nitrite Reactions With Hemoglobin: R-state Catalysis, Oxidative Denitrosylation, and Nitrite reductase/anhydrase

Abstract: Because of their critical biological roles, hemoglobin and myoglobin are among the most extensively studied proteins in human history, while nitrite tops the list of most-studied small molecules. And although the reactions between them have been examined for more than 140 years, a series of unusual and critical allosterically modulated reactions have only recently been characterized. In this Account, we review three novel metal- and nitrite-catalyzed reaction pathways in the context of historical studies of nitrite and hemoglobin chemistry and attempt to place them in the biological framework of hypoxic signaling. Haldane first described the reaction between nitrite and deoxymyoglobin, forming iron-nitrosylated myoglobin, in his analysis of the meat-curing process more than a century ago. The reaction of nitrous acid with deoxyhemoglobin to form nitric oxide (NO) and methemoglobin was more fully characterized by Brooks in 1937, while the mechanism and unusual behavior of this reaction were further detaile...

Hypoxia reprograms calcium signaling and regulates myoglobin expression

Abstract: Myoglobin is an oxygen storage molecule that is selectively expressed in cardiac and slow-twitch skeletal muscles that have a high oxygen demand. Numerous studies have implicated hypoxia in the regulation of myoglobin expression as an adaptive response to hypoxic stress. However, the details of this relationship remain undefined. In the present study, adult mice exposed to 10% oxygen for periods up to 3 wk exhibited increased myoglobin expression only in the working heart, whereas myoglobin was either diminished or unchanged in skeletal muscle groups. In vitro and in vivo studies revealed that hypoxia in the presence or absence of exercise-induced stimuli reprograms calcium signaling and modulates myoglobin gene expression. Hypoxia alone significantly altered calcium influx in response to cell depolarization or depletion of endoplasmic reticulum calcium stores, which inhibited the expression of myoglobin. In contrast, our whole animal and transcriptional studies indicate that hypoxia in combination with exercise enhanced the release of calcium from the sarcoplasmic reticulum via the ryanodine receptors triggered by caffeine, which increased the translocation of nuclear factor of activated T-cells into the nucleus to transcriptionally activate myoglobin expression. The present study unveils a previously unrecognized mechanism where the hypoxia-mediated regulation of calcium transients from different intracellular pools modulates myoglobin gene expression. In addition, we observed that changes in myoglobin expression, in response to hypoxia, are not dependent on hypoxia-inducible factor-1 or changes in skeletal muscle fiber type. These studies enhance our understanding of hypoxia-mediated gene regulation and will have broad applications for the treatment of myopathic diseases.

The distal pocket histidine residue in horse heart myoglobin directs the O-binding mode of nitrite to the heme iron.

Abstract: It is now well-established that mammalian heme proteins are reactive with various nitrogen oxide species and that these reactions may play significant roles in mammalian physiology. For example, the ferrous heme protein myoglobin (Mb) has been shown to reduce nitrite (NO2−) to nitric oxide (NO) under hypoxic conditions. We demonstrate here that the distal pocket histidine residue (His64) of horse heart metMbIII (i.e., ferric MbIII) has marked effects on the mode of nitrite ion coordination to the iron center. X-ray crystal structures were determined for the mutant proteins metMbIII H64V (2.0 A resolution) and its nitrite ion adduct metMbIII H64V−nitrite (1.95 A resolution), and metMbIII H64V/V67R (1.9 A resolution) and its nitrite ion adduct metMbIII H64V/V67R−nitrite (2.0 A resolution). These are compared to the known structures of wild-type (wt) hh metMbIII and its nitrite ion adduct hh metMbIII−nitrite, which binds NO2− via an O-atom in a trans-FeONO configuration. Unlike wt metMbIII, no axial H2O is e...

The amino acid sequence of myoglobin from the mollusc Aplysia limacina.

Abstract: The amino acid sequence of the globin prepared from the myoglobin contained in the radular muscle of the gasteropod mollusc Aplysia limacina was determined. According to the results thus obtained, the polypeptide chain of Aplysia limacina myoglobin is composed of 145 amino acid residues, in good agreement with the overall number of amino acid residues contained in the polypeptide chain of the vertebrate myoglobins studied to date. A particularly interesting feature of the myoglobin studied appears to be the presence in its polypeptide chain of only one histidine which occupies the 95th position.

Expression and functional regulation of myoglobin in epithelial cancers.

Abstract: Myoglobin is a multifunctional heme protein that is thought to be expressed exclusively in myocytes. Its importance in both oxygen transport and free radical scavenging has been extensively characterized. We hypothesized that solid tumors could take advantage of proteins such as myoglobin to cope with hypoxic conditions and to control the metabolism of reactive oxygen and nitrogen species. We therefore sought to establish whether myoglobin might be expressed and functionally regulated in epithelial tumors that are known to face hypoxia and oxidative stress during disease progression. We analyzed the expression of myoglobin in human epithelial cancers at both transcriptional and protein levels; moreover, we investigated the expression levels of myoglobin in cancer cell lines subjected to different conditions, including hypoxia, oxidative stress, and mitogenic stimuli. We provide evidence that human epithelial tumors, including breast, lung, ovary, and colon carcinomas, express high levels of myoglobin from the earliest stages of disease development. In human cancer cells, myoglobin is induced by a variety of signals associated with tumor progression, including mitogenic stimuli, oxidative stress, and hypoxia. This study provides evidence that myoglobin, previously thought to be restricted to myocytes, is expressed at high levels by human carcinoma cells. We suggest that myoglobin expression is part of a cellular program aimed at coping with changed metabolic and environmental conditions associated with neoplastic growth.

Pattern of cavities in globins: The case of human hemoglobin†

Abstract: Our aim is to shed light on the conservation of potential ligand docking sites that play an important role in ligand dynamics of globins by using the technique of filling internal cavities naturally present in hemoglobin and myoglobin with xenon atoms In particular, we present the high resolution structures of the Xe-adduct of deoxygenated wild type human hemoglobin and a quadruple mutant (L(B10)Y and H(E7)Q in alpha and beta chains) For the sake of comparison we also determined under the same experimental conditions the xenon complex of wild type sperm whale myoglobin The analysis revealed that the number and position of Xe binding cavities are different in the alpha and beta subunits, the latter being more similar to myoglobin Notably, no proximal Xe docking site was detected in hemoglobin, at variance with myoglobin The pattern of internal cavities accessibility and affinity for xenon suggests a different role for the dynamics of ligand migration in the two types of hemoglobin chains as compared to myoglobin The number and position of hydrophobic cavities in hemoglobin are briefly discussed also in comparison with the data available for other members of the globin superfamily

Meso-unsubstituted iron corrole in hemoproteins: remarkable differences in effects on peroxidase activities between myoglobin and horseradish peroxidase.

Abstract: Myoglobin (Mb) and horseradish peroxidase (HRP) were both reconstituted with a meso-unsubstituted iron corrole and their electronic configurations and peroxidase activities were investigated. The appearance of the 540 nm band upon incorporation of the iron corrole into apoMb indicates axial coordination by the proximal histidine imidazole in the Mb heme pocket. Based on 1H NMR measurements using the Evans method, the total magnetic susceptibility of the iron corrole reconstituted Mb was evaluated to be S = 3/2. In contrast, although a band does not appear in the vicinity of 540 nm during reconstitution of the iron corrole into the matrix of HRP, a spectrum similar to that of the iron corrole reconstituted Mb is observed upon the addition of dithionite. This observation suggests that the oxidation state of the corrole iron in the reconstituted HRP can be assigned as +4. The catalytic activities of both proteins toward guaiacol oxidation are quite different; the iron corrole reconstituted HRP decelerates H2...

Probing the electronic structure of the hemoglobin active center in physiological solutions.

Abstract: Soft-x-ray absorption spectroscopy at the L_{2,3} edge of the iron center in bovine hemoglobin and hemin under physiological conditions is reported for the first time. Spectra of the same compounds in solid form are presented for comparison. Striking differences in the electronic structure of the metalloporphyrin are observed between the liquid and solid compounds. We unambiguously show that hemoglobin and hemin are in a high-spin ferric state in solution, and that the 2p spin-orbit coupling decreases for hemin compared to the hemoglobin, while this is not the case in solids. The spectra were simulated using ligand field multiplet theory, in good agreement with the experiment, allowing quantification of the amount of charge transfer between the porphyrin and Fe3+ ion in hemoglobin and in hemin.

The millisecond intermediate in the reaction of nitric oxide with oxymyoglobin is an iron(III)--nitrato complex, not a peroxynitrite.

Abstract: The dioxygenation of nitric oxide by oxyheme in globin proteins is a major route for NO detoxification in aerobic biological systems. In myoglobin, this reaction is thought to proceed through an iron(III)-bound peroxynitrite before homolytic cleavage of the O-O bond to form an iron(IV)-oxo and NO(2) radical followed by recombination and nitrate production. Single turnover experiments at alkaline pH have revealed the presence of a millisecond high-spin heme intermediate. It is widely presumed that this species is an iron(III)-peroxynitrite species, but detailed characterization of the intermediate is lacking. Using resonance Raman spectroscopy and rapid-freeze quench techniques, we identify the millisecond intermediate as an iron(III)-nitrato complex with a symmetric NO(2) stretch at 1282 cm(-1). Greater time resolution techniques will be required to detect the putative iron(III) peroxynitrite complex.

Structure and Catalytic Behavior of Myoglobin Adsorbed onto Nanosized Hydrotalcites

Abstract: The adsorption of myoglobin (Mb) onto nanosized nickel aluminum hydrotalcite (NiAl-HTlc) surface was studied, and the structural properties of the resulting protein layer were analyzed by using FT-IR, Raman, and fluorescence spectroscopies. Upon adsorption onto the nanoparticle surface, the protein molecules maintained their secondary structure, while the tertiary structure was altered. The fluorescence spectra and anisotropy values of adsorbed Mb revealed that the emitting amino acid residues are affected by different microenvironments when compared to the native protein behavior. Moreover, the decrease of fluorescence decay times of tryptophan indicated the occurrence of interactions among the fluorophores and the constituents of the nanoparticles, such as the metal cations, which can take place when conformational changes of Mb occur. Raman spectra indicated that the interaction of Mb molecules with NiAl-HTlc nanoparticles modified the porphyrin core, changing the spin state of the heme iron from high ...

The value of serum myoglobin determinations in the early diagnosis of acute myocardial infarction.

Abstract: Myoglobin has been measured in sera from 305 consecutive patients with suspected acute myocardial infarction (AMI) to study the clinical value in relation to other diagnostic methods. On admission the frequency of false negative (i.e. the diagnostic sensitivity) myoglobin values was 28% in the AMI group as compared with 60% for serum creatine kinase (CK) and 46% for serum aspartate aminotransferase (ASAT). Four hours after admission the corresponding figures were 2, 31 and 29%. This makes the diagnostic sensitivity of the myoglobin test 0.98, which is significantly higher (p less than 0.001) than that of the two enzyme tests. The predictive value of a negative myoglobin test was 0.97 and also significantly higher (p less than 0.001 and p less than 0.01) than for CK and ASAT. S-myoglobin was further related to the number of complications and the prognosis of the patients, and high levels appeared to be an unfavourable sign, particularly in combination with an anterior wall infarct. This study has demonstrated and confirmed the superior diagnostic sensitivity of myoglobin determination in early AMI. The inclusion of S-myoglobin in the routine diagnosis of AMI warrants serious consideration.

High pressure reveals structural determinants for globin hexacoordination: Neuroglobin and myoglobin cases

Abstract: The influence of pressure on the equilibrium between five-(5c) and six-coordination (6c) forms in neuroglobin (Ngb) and myoglobin (Mb) has been examined by means of molecular dynamics (MD) simulations at normal and high pressure. The results show that the main effect of high pressure is to reduce the protein mobility without altering the structure in a significant manner. Moreover, our data suggest that the equilibrium between 5c and 6c states in globins is largely controlled by the structure and dynamics of the C-D region. Finally, in agreement with the available experimental data, the free energy profiles obtained from steered MD for both proteins indicate that high pressure enhances hexacoordination. In Ngb, the shift in equilibrium is mainly related to an increase in the 6c→5c transition barrier, whereas in Mb such a shift is primarily due to a destabilization of the 5c state. Proteins 2009. © 2008 Wiley-Liss, Inc.

Distal histidine conformational flexibility in dehaloperoxidase from Amphitrite ornata

Abstract: The enzyme dehaloperoxidase (DHP) from the terebellid polychaete Amphitrite ornata is a heme protein which has a globin fold but can function as both a hemoglobin and a peroxidase. As a peroxidase, DHP is capable of converting 2,4,6-trihalophenols to the corresponding 2,6-dihaloquinones in the presence of hydrogen peroxide. As a hemoglobin, DHP cycles between the oxy and deoxy states as it reversibly binds oxygen for storage. Here, it is reported that the distal histidine, His55, exhibits conformational flexibility in the deoxy form and is consequently observed in two solvent-exposed conformations more than 9.5 A away from the heme. These conformations are analogous to the open conformation of sperm whale myoglobin. The heme iron in deoxy ferrous DHP is five-coordinate and has an out-of-plane displacement of 0.25 A from the heme plane. The observation of five-coordinate heme iron with His55 in a remote solvent-exposed conformation is consistent with the hypothesis that His55 interacts with heme iron ligands through hydrogen bonding in the closed conformation. Since His55 is also displaced by the binding of 4-iodophenol in an internal pocket, these results provide new insight into the correlation between heme iron ligation, molecular binding in the distal pocket and the conformation of the distal histidine in DHP.

Dielectric Relaxations in Confined Hydrated Myoglobin

Abstract: In this work we report the results of a broadband dielectric spectroscopy study on the dynamics of a globular protein, myoglobin, in confined geometry, i.e. encapsulated in a porous silica matrix, at low hydration levels, where about only one or two water layers surround the proteins. In order to highlight the specific effect of confinement in the silica host, we compared this system with hydrated myoglobin powders at the same hydration levels. The comparison between the data relative to the two different systems indicates that geometrical confinement within the silica matrix plays a crucial role in protein−water dielectric relaxations, the effect of sol−gel encapsulation being essentially a suppression of cooperative relaxations that involve the coherence/cooperativity of solvent motions and solvent-coupled protein dynamics. We also provide direct evidence that protein relaxations inside the gel depend on the hydration level and are “slaved” to the solvent β-relaxation.

Demonstration of sandwich and competitive modulated supraparticle fluoroimmunoassay applied to cardiac protein biomarker myoglobin

Abstract: Modulated supraparticle structures are used to improve sandwich and competitive fluoroimmunoassays. The improved methods are demonstrated on myoglobin, a key diagnostic protein for detection of heart damage. The resulting method uses microliter volumes with bovine serum samples doped with varying concentrations of equine myoglobin. These immunoassays use micron-diameter iron oxide particles as a solid phase for antibody anchoring. Introduction of a magnetic field creates dipole moments on the particles, which attracts them to each other to form rod-like supraparticle structures. These structures can rotate within an alternating magnetic field generating convective flow and a periodic signal that can be analyzed with lock-in amplification enabling more sensitive detection. The system is demonstrated on a target associated with acute myocardial infarction (AMI). This disease causes decreased oxygen delivery to the heart resulting in tissue death and the release of cardiac myoglobin into the bloodstream. Studies have shown that the assessment and monitoring of serum myoglobin concentrations is important when making an early diagnosis of AMI. Early diagnosis is crucial since treatment is most effective when done within the first two hours of symptoms. The modulated assay is rapid, accurate, and sensitive for myoglobin assessment of small-volume serum samples. Using a cut-off value of 5.0 nM (85 ng/mL) for AMI induced myoglobin, the modulated competitive assay was able to diagnose AMI-like conditions in serum doped with myoglobin after an incubation time of only 10 min. The standard curve developed for the modulated sandwich assay was linear over a range of zero to 1 nM (17 ng/mL) with a lower limit of detection at 50 pM (0.85 ng/mL).

Breathing motions of a respiratory protein revealed by molecular dynamics simulations.

Abstract: Internal cavities, which are central to the biological functions of myoglobin, are exploited by gaseous ligands (e.g., O2, NO, CO, etc.) to migrate inside the protein matrix. At present, it is not ...

Noncovalent modulation of pH-dependent reactivity of a Mn-salen cofactor in myoglobin with hydrogen peroxide.

Abstract: To demonstrate protein modulation of metal-cofactor reactivity through noncovalent interactions, pH-dependent sulfoxidation and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) oxidation reactivity of a designed myoglobin (Mb) containing non-native Mn-salen complex (1) was investigated using H2O2 as the oxidant. Incorporation of 1 inside the Mb resulted in an increase in the turnover numbers through exclusion of water from the metal complex and prevention of Mn-salen dimer formation. Interestingly, the presence of protein in itself is not enough to confer the increase activity as mutation of the distal His64 in Mb to Phe to remove hydrogen-bonding interactions resulted in no increase in the turnover numbers, while mutation His64 to Arg, another residue with ability to hydrogen-bond interactions, resulted in an increase in reactivity. These results strongly suggest that the distal ligand His64, through its hydrogen-bonding interaction, plays important roles in enhancing and fine-tuning reactivity of the Mn-salen complex. Nonlinear least-squares fitting of rate versus pH plots demonstrates that 1.Mb(H64X) (X=H, R and F) and the control Mn-salen 1 exhibit pKa values varying from pH 6.4 to 8.3, and that the lower pKa of the distal ligand in 1.Mb(H64X), the higher the reactivity it achieves. Moreover, in addition to the pKa at high pH, 1.Mb displays another pKa at low pH, with pKa of 5.0+/-0.08. A comparison of the effect of different pH on sulfoxidation and ABTS oxidation indicates that, while the intermediate produced at low pH conditions could only perform sulfoxidation, the intermediate at high pH could oxidize both sulfoxides and ABTS. Such a fine-control of reactivity through hydrogen-bonding interactions by the distal ligand to bind, orient and activate H2O2 is very important for designing artificial enzymes with dramatic different and tunable reactivity from catalysts without protein scaffolds.

On the content of myoglobin in human muscles.

Abstract: A quantitative method of determining the content of myoglobin and hemoglobin in human muscle is described. A piece of muscle, 1–4 g, is ground with dry ice, homogenized and extracted with 0.02 M phosphate buffer, pH 7.4. After being centrifuged at 15,000 × g, the solution is concentrated by dialysis against 25% polyethylene glycol solution. The hemoproteins are separated by gel filtration on Sephadex G 75, identified by the absorption spectra of their carbon monoxide compounds and quantitatively determined by the pyridine hemochrome method. The content of hemoprotein is calculated as per cent of dry weight, the latter being determined on the original homogenate. In an autopsy material, mainly consisting of patients in upper age-groups with chronic disease and modest physical activity, average values of 0.9 g myoglobin per 100 g dry muscle were found in hearts (left ventricle), whereas corresponding values for diaphragm, abdominal muscle and muscles of the thigh were 1.1, 1.6 and 2.2 g per 100 g dry muscle. It is assumed that values in healthy adults may well be somewhat higher. From these values it is calculated that the total amount of myoglobin in an adult male is in the range of 120–150 g, corresponding to an iron pool of 0.37-0.47 g or approximately 7/5 of the amount of hemoglobin iron. Comparisons with determinations arrived at by other methods are made, and some aspects of the physiology of myoglobin and other hematin compounds are discussed. The insoluble or “residual” hematin has been determined. It could be shown that the major part of this hematin can be accounted for by the mitochondrial hemoproteins, the remaining part in all probability deriving from hemoglobin.

Both hypoxia and work are required to enhance expression of myoglobin in skeletal muscle. Focus on Hypoxia reprograms calcium signaling and regulates myoglobin expression

Abstract: the effects of hypoxia on mammalian heart and muscle have fascinated physiologists for many a day. Myoglobin is expressed adaptively in muscle. In very young animals, and in the absence of muscle work, the myoglobin concentration in muscles remains very small. What factors lead to myoglobin genesis

Kinetics of carbon monoxide migration and binding in solvated neuroglobin as revealed by molecular dynamics simulations and quantum mechanical calculations.

Abstract: By using multiple (independent) molecular dynamics (MD) trajectories (about 500 ns in total) of photolized carbon monoxide (CO) within solvated myoglobin, a quantitative description of CO migration and corresponding kinetics is obtained. MD results combined with previously reported quantum mechanical calculations on the CO-heme binding-unbinding reaction step in myoglobin allowed construction of a detailed quantitative model, shedding light on the kinetic mechanism and relevant steps of CO migration and geminate binding. Finally, the obtained (unbiased) theoretical-computational model is critically compared with the available computational and experimental data for myoglobin in solution.

Identification of protein radicals formed in the human neuroglobin-H2O2 reaction using immuno-spin trapping and mass

Abstract: Neuroglobin (Ngb) is a recently discovered protein that shows only minor sequence similarity with myoglobin and hemoglobin but conforms to the typical 3-over-3 α-helical fold characteristic of vertebrate globins. An intriguing feature of Ngb is its heme hexacoordination in the absence of external ligands, observed both in the ferrous and ferric (met) forms. In Ngb, the imidazole of a histidine residue (His-64) in the distal position, above the heme plane, provides the sixth coordination bond. In this work, a valine residue was introduced at position 64 (H64V variant) to clarify the possible role(s) of the distal residue in protecting the heme iron of Ngb from attack by strong oxidants. SDS-PAGE analyses revealed that the oxidation of the H64V variant of metNgb by H2O2 resulted in the formation of dimeric and trimeric products in contrast to the native protein. Dityrosine crosslinks were shown by their fluorescence to be present in the oligomeric products. When the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was included in the reaction mixture, nitrone adducts were detected by immuno-spin trapping. The specific location of the DMPO adducts on the H64V variant protein was determined by a mass spectrometry method that combines off-line immuno-spin trapping and chromatographic procedures. This method revealed Tyr-88 to be the site of modification by DMPO. The presence of His-64 in the wild-type protein results in the nearly complete loss of detectable radical adducts. Together, the data support the argument that wild-type Ngb is protected from attack by H2O2 by the coordinated distal His.

Roles of the creatine kinase system and myoglobin in maintaining energetic state in the working heart

Abstract: The heart is capable of maintaining contractile function despite a transient decrease in blood flow and increase in cardiac ATP demand during systole. This study analyzes a previously developed model of cardiac energetics and oxygen transport to understand the roles of the creatine kinase system and myoglobin in maintaining the ATP hydrolysis potential during beat-to-beat transient changes in blood flow and ATP hydrolysis rate. The theoretical investigation demonstrates that elimination of myoglobin only slightly increases the predicted range of oscillation of cardiac oxygenation level during beat-to-beat transients in blood flow and ATP utilization. In silico elimination of myoglobin has almost no impact on the cytoplasmic ATP hydrolysis potential (ΔGATPase). In contrast, disabling the creatine kinase system results in considerable oscillations of cytoplasmic ADP and ATP levels and seriously deteriorates the stability of ΔGATPase in the beating heart. The CK system stabilizes ΔGATPase by both buffering ATP and ADP concentrations and enhancing the feedback signal of inorganic phosphate in regulating mitochondrial oxidative phosphorylation.

Myoglobin and mitochondria: Oxymyoglobin interacts with mitochondrial membrane during deoxygenation

Abstract: The rates of oxygen uptake by rat liver mitochondria (MC) (native coupled, freshly frozen, and uncoupled by FCCP) have been measured polarographically in the absence (V 0) or presence (V 1) of 0.11–0.25 mM sperm whale MbO2. Under the same standard conditions, the rate of sperm whale MbO2 deoxygenation (V 2) has been studied spectrophotometrically in the presence of respiring MC. For freshly frozen MC, the dependence of V 1 and V 2 on the overall charge of MbO2 has been investigated at pH 5.6–7.6, and the influence of other differently charged proteins (apomyoglobin, egg lysozyme, lactalbumin, and BSA) has been studied at pH 7.4. It is shown that the rate of mitochondrial respiration in the presence of MbO2 increases by 10–30% (V 1 > V 0). No myoglobin effect is observed for FCCP-uncoupled MC (V max does not change). The rate of MbO2 deoxygenation is equal to the rate of oxygen uptake by mitochondria (V 2/V 1 ∼ 1 at pH 7.2–7.5). At varying pH < 7.2, the V 2 values become markedly higher than V 1, evidently due to the increased MbO2 positive charge and its stronger interaction with negatively charged mitochondrial membrane. At pH 7.4, on the contrary, V 2 is twice lower than V 1 in the case of negatively charged CM-MbO2 (pI 5.2), which has carboxymethylated histidines. Positively charged lysozyme (pI 11) strongly inhibits MbO2 deoxygenation (V 2) without affecting oxygen uptake by MC (V 0 and V 1). At the same time, apomyoglobin (pI 8.5), which is structurally very similar to the holoprotein, and both negatively charged lactalbumin (pI 4.4) and BSA (pI 4.7) have no substantial influence on V 2 and V 1. The MC membrane evidently has no specific sites for the interaction with myoglobin. Rather, the protein contacts with phospholipids of the outer membrane during MbO2 deoxygenation, and electrostatic interactions are of great importance for this process.

Myoglobin concentration in skeletal muscle fibers of chronic heart failure patients.

Abstract: The purpose of this study was to determine the myoglobin concentration in skeletal muscle fibers of chronic heart failure (CHF) patients and to calculate the effect of myoglobin on oxygen buffering...