Disease relevance of MB

• On the other hand, the serum levels of myoglobin, cardiac troponin I and creatine kinase MB isoenzyme suggest the ability of the aminosteroid to attenuate the modifications of membrane permeability induced by ischemia-reperfusion injury [1].
• Cardiac proteins were released in all pigs with stenosis of the LAD artery during the development of myocardial ischemia; the levels of cTnI, CK-MB, and myoglobin increased significantly relative to the baseline [2].
• To assess the impact of thiol supplementation on a fully integrated model of heme protein toxicity, proximal tubular (HK-2) cells were cultured with myoglobin x 24 hours +/- test reactants [3].
• During ischemia, myoglobin desaturation and cytochrome reduction were delayed and less complete in the presence of propofol [4].
• Myocardial mean myoglobin oxygen saturation was determined spectroscopically from isolated guinea pig hearts perfused with red blood cells during increasing hypoxia [5].

High impact information on MB

• In vitro studies demonstrated that NO was able to reduce the reactive oxygen species produced by myoglobin, especially oxoferrylmyoglobin, which either are present in heart or are formed in high concentrations during the reperfusion of ischemic myocardium [6].
• Neither the carbon monoxide scavenger myoglobin (5-20 microm) nor the guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one could reverse ASM proliferation induced by tin-protoporphyrin, making a role of the CO-cGMP pathway in HO-modulated proliferation unlikely [7].
• All of these results suggest strongly that azide enters the distal pocket of native myoglobin through a polar channel that is regulated by a His64 "gate." In contrast to azide binding, the rate constant for cyanide association decreases 4-300-fold when the distal histidine is replaced with apolar residues [8].
• When beta-lactoglobulin A, melittin, serum albumin, myoglobin, and a protein inhibiting lipase from soybean were preincubated with a dicaprin film at a surface pressure of 35 dynes/cm, no activity was detected with horse pancreatic or Rhizopus delemar lipases [9].
• The ferric quadruple mutants show a clear water/hydroxide alkaline transition and high cyanide and CO affinities, characteristics similar to those of wild-type myoglobin [10].

Chemical compound and disease context of MB

• Conversely, cysteine (but not homocysteine) decreased myoglobin toxicity [3].
• This is due to lower levels of myoglobin and histidine in the young, which could render them more susceptible to injury during ischemia [11].
• Cardioprotection of cariporide evaluated by plasma myoglobin and troponin I in myocardial infarction in pigs [12].
• Although lactate accumulation during 1 h of global ischemia was similar between ventricles of neonatal and adult swine, H(+) accumulation was greater and BC, Mb and His content were lower [11].

Biological context of MB

• Porcine myoglobin cDNA clones have been isolated from a cDNA library prepared from enriched heart-myoglobin mRNA [13].
• Mean myoglobin saturation, ventricular function, and oxygen consumption remained fairly constant for arterial perfusate oxygen tensions above 100 mmHg and then decreased precipitously below 100 mmHg [5].
• In contrast, mean myoglobin saturation, ventricular function, and oxygen consumption began to decrease even at high oxygen tension with buffer perfusion [5].
• It was found that during perfusion with a hematocrit of 5%, baseline mean myoglobin saturation was 93% compared with 72% during buffer perfusion [5].
• MEASUREMENTS AND MAIN RESULTS: Myoglobin oxygen saturation, cytochrome c and cytochrome a/a3 redox state, and ventricular pressure were continuously measured from isolated guinea pig hearts during a 2-hr period [4].

Anatomical context of MB

• The present results demonstrate that perfusion with 5% red blood cells in the perfusate increases the baseline mean myoglobin saturation and better preserves cardiac function at low oxygen tension relative to buffer perfusion [5].
• A simple spectroscopic method for determining the cytochrome c oxidase, cytochrome a, a3, content in tissue and mitochondria samples independent of myoglobin or blood contamination is described [14].
• Flux-decline data were obtained for the filtration of bovine serum albumin, lysozyme, pepsin, immunoglobulin G, and myoglobin through polycarbonate track-etch membranes [15].
• The left circumflex coronary artery was ligated for 60-min and then reperfused for 48-h. Plasma levels of myoglobin and troponin I were quantified during reperfusion [12].
• Mb positive cells of various degrees were detected in all thymuses of both groups, and immunoelectron microscopical examination disclosed that Mb positive cells corresponded to interdigitating reticulum cells and myoid cells in non-neoplastic thymuses, and neoplastic epithelial reticular cells in thymomas [16].

Associations of MB with chemical compounds

• In the mollusc myoglobin, arginine-E10 is believed to swing into the heme pocket and provide a hydrogen bond to the bound O2 [17].
• The 2D 1H-NMR measurements of the CO complexes show that mutation of Ser92 to Ala changes the relative position of the His97 imidazole group to the heme plane, but the change is not so drastic as reported in the crystal data of Ser92 mutant of pig Mb [Smerdon et al. (1993) Biochemistry 32, 5132-5138] [18].
• Stabilizing bound O2 in myoglobin by valine68 (E11) to asparagine substitution [19].
• Differential effects of glutathione and cysteine on Fe2+, Fe3+, H2O2 and myoglobin-induced proximal tubular cell attack [3].
• The effects of mutation of the conserved serine92 residue to alanine, valine, and leucine in pig myoglobin have been determined [20].

Other interactions of MB

• The sensitivity and specificity for cTnI were higher than for CK-MB or myoglobin [2].
• RESULTS: The following proteins of boar prostate secretion were identified: beta-microseminoprotein, serotransferrin, serum albumin, myoglobin and PSP I and PSP II spermadhesins [21].
• Reduced cytochrome-c, reduced myoglobin and oxyhemoglobin respectively have been oxidized to oxidized cytochrome-c, metmyoglobin and methemoglobin by ceruloplasmin [22].
• The filtration properties of the films were examined using cytochrome c, myoglobin, lysozyme, ovalbumin, lactoglobulin, and serum albumin [23].
• Blood samples were drawn for measurement of aspartate aminotransferase, alanine aminotransferase, lactic dehydrogenase and myoglobin with the objective of verifying myocardial damage [24].

Analytical, diagnostic and therapeutic context of MB

• Cloning and sequence analysis of porcine myoglobin cDNA [13].
• Spectroscopic and ligand binding properties have been measured for human and pig H64V/V68H myoglobin, and the structure of the pig H64V/V68H double mutant has been determined to 2.07-A resolution by x-ray crystallography [25].
• The concentration of myoglobin in the hemoperfusate remained within normal values and was similar during autologous and xenogeneic perfusion [26].
• A ligand binding pocket has been created on the proximal side of the heme in porcine myoglobin by site-directed mutagenesis [10].
• Neutron diffraction studies have demonstrated that the hydroxyl group oxygen of Ser92(F7) is hydrogen bonded to the proximal His93(48) N epsilon H proton in myoglobin (Mb) [Cheng, X., & Shoenborn, B. P. (1991) J. Mol. Biol. 220, 381-399] [18].

References