Disease relevance of MB

• The rates of MB oxidation were similar (P > 0.05) for sterile and frozen-thawed inoculated (Pseudomonas fluorescens at a rate of 1.5 colony forming units/cm(2).cm(2) area) samples from day 0 through day 6 of storage [1].
• The degree to which the decrease in pH and the freeing of copper ions, as well as the variations in pO2 associated with ischemia and reperfusion increase the rates of such myoglobin reactions has been investigated [2].
• Potential roles of myoglobin autoxidation in myocardial ischemia-reperfusion injury [2].
• Thus myoglobin is critical to O2 supply at fluxes near the maximum and prevents anoxia by maintaining PO2 above levels needed to support mitochondrial function [3].
• Ferryl Mb, but not ferryl DBBF-Hb, was observed in samples analyzed at the end of treatment, which may explain the greater toxicity observed with Mb as opposed to DBBF-Hb [4].

High impact information on MB

• Myoglobin diffusion in bovine heart muscle [5].
• Dynamic protein structures: infrared evidence for four discrete rapidly interconverting conformers at the carbon monoxide binding site of bovine heart myoglobin [6].
• Gas chromatography-mass spectroscopy analysis of the evolved O2 from a 50:50 mixture of H2(18)O2/H2(16)O2 solution containing H64D or F43H/H64L Mb showed the formation of 18O2 (m/e = 36) and 16O2 (m/e = 32) but not 16O18O (m/e = 34) [7].
• In contrast, other Mb mutants such as H64X (X is Ala, Ser, and Asp) and L29H/H64L Mb oxidize H2O2 via a radical mechanism in which a hydrogen atom is abstracted by Mb-I with a large isotope effect in a range of 10-29, due to a lack of the general acid-base catalyst [7].
• Compound I of Mb mutants (Mb-I), a ferryl species (Fe(IV)=O) paired with a porphyrin radical cation, is readily prepared by the reaction with a nearly stoichiometric amount of m-chloroperbenzoic acid [7].

Chemical compound and disease context of MB

• Effects of hypoxia and glutathione depletion on hemoglobin- and myoglobin-mediated oxidative stress toward endothelium [4].
• Incubation of diaspirin cross-linked hemoglobin (DBBF-Hb) or horse skeletal myoglobin (Mb) with BAECs subjected to 3 h of hypoxia caused transient oxidation of the hemoproteins to the ferryl form (Fe(4+)) [4].

Biological context of MB

• A role for the myoglobin redox cycle in the induction of endothelial cell apoptosis [8].
• Mb and Mb/GOX suppressed cell cycle progression, but only Mb/GOX produced significant cell loss revealed by the accumulation of sub G1 events [8].
• The rate of conversion from Fe3+ to the reduced Fe2+ in myoglobin, under given electrophoretic conditions, followed first-order kinetics with a rate constant at 30 degrees C of 304 s-1 [9].
• In the molecular evolution from simple ferrous complexes to myoglobin and hemoglobin molecules, therefore, the protein matrix can be depicted as a breakwater of the FeO2 bonding against protic, aqueous solvents [10].
• The experimental results are described in terms of a dynamic docking model which proposes that Mb binds cyt b(5) in a large ensemble of protein binding conformations, not one or a few dominant ones, but that only a small subset are ET reactive [11].

Anatomical context of MB

• We isolated a cDNA clone for myoglobin mRNA from fetal bovine skeletal muscle using a DNA fragment of human myoglobin exon 2 as a probe [12].
• Bovine aortic endothelial cells were incubated with ferric Mb (0.5-100 micro M) in the presence or absence of low steady states of H(2)O(2) (3-4 micro M) generated by glucose oxidase (GOX) [8].
• The fragments released by cathepsin D contain most, if not all, major epitopes for murine myoglobin-specific helper T cells [13].
• This synergism may be particularly relevant to the protection of myoglobin-rich cells such as myocytes [14].
• It is demonstrated that such a system yields fragments that are indistinguishable by high performance liquid chromatography analysis from those generated after uptake of myoglobin inside live macrophages [13].

Associations of MB with chemical compounds

• N-terminal sequence analysis of the produced myoglobin revealed a glycine residue at the terminus, indicating that as in native muscle the N-terminal Met was removed in yeast by processing [12].
• Epoxidation of styrene by hemoglobin and myoglobin. Transfer of oxidizing equivalents to the protein surface [15].
• Demonstration of enzymatic activity is dependent on a suitable myoglobin substrate, NADH, and ferrocyanide [16].
• In contrast to a published report (Gloster, J., and Harris, P. (1977) Biochem. Biophys. Res. Commun. 74, 506-513), oleic acid was not bound by rat heart or bovine heart myoglobin [17].
• This study suggests a function for the three exterior lysine residues conserved in all mammalian myoglobin sequences: they are contact points for complexation with cytochrome b5 [18].

Other interactions of MB

• Noncovalent bonding interactions of nitric oxide (NO) with human serum albumin (HSA), human hemoglobin A, bovine myoglobin, and bovine cytochrome c oxidase (CcO) have been explored [19].
• Intact haemoproteins such as cytochrome c and myoglobin were not effective substrates [20].
• OBJECTIVE: The aim was to investigate the interaction of the novel antioxidant N-methyl hexanoylhydroxamic acid (NMHH) with myoglobin in protecting endothelial cells against H2O2 mediated damage [14].
• Cathepsin D appears to be mainly responsible for the initial cleavage of myoglobin, while cathepsin B catalyzes the C-terminal trimming of initially released fragments [13].
• Whereas the heme which was present in the cyanogen bromide digest of myoglobin desorbed as the second peak from the RP-8 column, it eluted last from the adsorbed stationary phase [21].

Analytical, diagnostic and therapeutic context of MB

• Paramyxovirus membrane (M) protein specifically binds to cellular actin but not to bovine serum albumin or myoglobin, as determined by affinity chromatography and enzyme-linked immunosorbent assay [22].
• Thus crystallization of this enzyme does not affect the structure at the CO-binding site to as great extent as has been noted for myoglobin and hemoglobin carbonyls, indicating that the active (CO- or O2-binding) site of cytochrome c oxidase must be conformationally very stable and highly ordered compared to other hemoproteins such as hemoglobin [23].
• Influence of column temperature on the electrophoretic behavior of myoglobin and alpha-lactalbumin in high-performance capillary electrophoresis [9].
• LC-MS revealed the covalent binding of HNE to Mb at both pH values via Michael addition, while Western blot analysis indicated that HNE was bound to histidine (HIS) residues [24].
• Using the manipulation force microscope, a novel atomic force microscope, the adhesion forces of bovine serum albumin, myoglobin, ferritin, and lysozyme proteins to glass and polystyrene substrates were characterized by following the force necessary to displace an adsorbed protein-covered microsphere over several orders of magnitude in time [25].

References