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At least 19 recordsLinked to original sources
PubMed1980

The antibody response to myoglobin is independent of the immunized species. Analysis in terms of replacements in the antigenic sites and in environmental residues of the cross-reactions of fifteen myoglobins with sperm-whale myoglobin antisera raised in different species.

The recent determination of the entire antigenic structure of sperm-whale myoglobin with rabbit and goat antisera has permitted the examination of whether the antigenic structure recognized by antibodies depends on the species in which the antisera are raised. Also, by knowledge of the antigenic structure, the molecular factors that determine and influence antigenicity can be better understood in terms of the effects of amino acid substitutions occurring in the antigenic sites and in the environmental residues of the sites. In the present work, the myoglobins from finback whale, killer whale, horse, chimpanzee, sheep, goat, bovine, echidna, viscacha, rabbit, dog, cape fox, mouse and chicken were examined for their ability to cross-react with antisera to sperm-whale myoglobin. By immunoadsorbent titration studies with radioiodinated antibodies, each of these myoglobins was able to bind antibodies to sperm-whale myoglobin raised in goat, rabbit, chicken, cat, pig and outbred mouse. It was found that the extent of cross-reaction of a given myoglobin was not dependent on the species in which the antisera were raised. This indicated that the antibody response to sperm-whale myoglobin (i.e. its antigenic structure) is independent of the species in which the antisera are raised and is not directed to regions of sequence differences between the injected myoglobin and the myoglobin of the immunized host. Indeed, in each antiserum from a given species examined, that antiserum reacted with the myoglobin of that species. The extent of this auto-reactivity for a given myoglobin was comparable with the general extent of cross-reactivity shown by that myoglobin with antisera raised in other species. The cross-reactivities and auto-reactivities (both of which are of similar extents for a given myoglobin) can be reasonably rationalized in terms of the effects of amino acid substitutions within the antigenic sites and within the residues close to these sites. These findings confirm that the antigenicity of the sites is inherent in their three-dimensional locations.

Amino Acid Sequence↗
PubMed1986

Myoglobin expression: early induction and subsequent modulation of myoglobin and myoglobin mRNA during myogenesis.

We showed that myoglobin gene transcription and the appearance of myoglobin occur very early in myogenesis, in both humans and mice. In contrast to the contractile protein genes, there is a subsequent increase of 50- to 100-fold in myoglobin mRNA and protein levels during later muscle development. Myoglobin and myoglobin mRNA are present at elevated levels in fetal heart and are also detectable at low levels in adult smooth muscle. The absolute level of myoglobin mRNA in highly myoglobinized seal muscle is very high [2.8% of the total population of poly(A)+ RNAs]. Levels of myoglobin in seal skeletal muscle and in various human muscle types appear to be determined by the size of the myoglobin mRNA pool. In contrast, low levels of myoglobin in mouse skeletal muscle are not apparently correlated with low levels of myoglobin mRNA. As expected from the early appearance of myoglobin mRNA in embryonic skeletal muscle, both rat and mouse embryonic myoblasts accumulate myoglobin mRNA on fusion and differentiation in vitro.

Actins↗
PubMed1981

Genetic control of the immune response to myoglobin. V. Analysis of the cross-reactivity of 12 myoglobins with sperm-whale myoglobin antisera of inbred mouse strains in terms of substitutions in the antigenic sites and in the environmental residues of the sites.

The determination of the entire antigenic structure of myoglobin has made it possible to focus attention on the molecular factors controlling and influencing immune recognition. Recently, using antisera raised against sperm-whale myoglobin (Mb) in six different host species and investigating their reactions with Mb from 15 species, we showed that the binding capacity of an antigenic site is influenced by substitutions within site residues as well as within the residues close (within 6.0 å) to the sites. Based on these effects it was possible to correlate, at least in qualitative terms, the expected effects of the substitutions in each Mb and its observed cross-reaction with antisera to sperm-whale Mb. In the present work, these correlations were tested using sperm-whale Mb antibodies raised in four inbred mouse strains and in which the amount of antibodies directed to each antigenic site was determined. The amounts of 125I-labelled antibodies that could be bound maximally be each of 12 Mb variants were determined. Because of genetic control, the response to some antigenic sites was not expressed and therefore permitted us to evaluate with a good degree of confidence the effects of amino acid replacements in various myoglobins upon the reactivity of the sites. The values of cross-reaction expected for each Mb variant from these considerations agreed well with the values found experimentally. The results confirm unambiguously that the major factors affecting the cross-reactions of proteins can be attributed to substitutions within the sites and within environmental residues of the sites.

Animals↗
PubMed1981

Genetic control of the immune response to myoglobin. VII. Antibody responses to myoglobin variants reveal that gene restriction of the antibody responses to myoglobin antigenic sites is dependent on the chemical properties of the sites.

Previously it has been shown that the immune responses to sperm-whale myoglobin are under H-2-linked Ir-gene control. More importantly the responses to the synthetic antigenic sites are each under separate genetic control. In the present studies we investigated the genetic control of the antibody response to four different myoglobins of known structure, to determine whether this genetic control is influenced by changes in the properties of the sites. The results suggest that genetic control of the responses to individual antigenic sites on a protein antigen is not only determined by the genetic constitution of the host species but also by the chemical properties of the individual sites. It appears that the H-2 subregions mapping the responses to given antigenic sites can also recognize other sites, which were previously unrecognizable in a homologous protein, if their chemical properties are suitably altered.

Animals↗
PubMed1982

Studies on reconstituted myoglobins and hemoglobins. I. Role of the heme side chains in the oxygenation of myoglobin.

To clarify the functional role of the 2- and 4-side chains of heme in myoglobin oxygenation, we synthesized several new hemins carrying nonnatural side chains at positions 2 and 4, reconstituted myoglobins with them, and investigated their optical, ionization, and oxygen-binding properties. The absorption maxima for most of the reconstituted myoglobins except those reconstituted with hemins having carbonyl groups, no matter whether they are oxy-, deoxy-, or carbon monoxy-form, shifted by at most 20 nm toward shorter wavelengths than protoheme-myoglobin. The absorption spectrum is more affected by resonance effects than by inductive effects of the peripheral side chains of heme. Differences in optical and oxygenation properties between isomeric myoglobins carrying hemes with different side chains at positions 2 and 4 indicate that the 2- and 4-side chains of heme are functionally nonequivalent, as previously shown by Sono and Asakura [(1975) J. Biol. Chem. 250, 5227-5232] for monoformyl-monovinylheme myoglobins. Modification of the 4-side chain exerts greater influence on the oxygen affinity than that of the 2-side chain. The extrapolation method proposed by Sono and Asakura to correct for the protein factor seems to be applicable only as a special case and does not apply to the isomeric myoglobins studied by us. There was not correlation between pKa of the met-form and the oxygen pressure at half saturation, implying that the electronic effect of the side chains is not decisive for the oxygen affinity of myoglobin. The bulkiness of the 2- and 4-side chains, on the other hand, appear to have a certain relation to the affinity but is not a dominant factor. In addition to these factors, specific stereochemical considerations are required to explain all the oxygenation data for the various reconstituted myoglobins. We have proposed a stereochemical mechanism based on the movement of the heme group upon ligation of native myoglobin.

Acylation↗
PubMed1989

Kinetics of myoglobin release and prediction of myocardial myoglobin depletion after coronary artery reperfusion.

To better define the usefulness of blood myoglobin measurements in evaluating the effectiveness of attempted thrombolysis, we studied the kinetics of myoglobin entry into and removal from the circulation after coronary artery reperfusion and the relation between directly measured depletion of myocardial myoglobin after coronary occlusion and reperfusion and the amount of depletion predicted from plasma myoglobin concentration-time curves. Initially, canine myoglobin was administered to 11 dogs by both bolus injection and 40-minute infusion, and the subsequent disappearance patterns of myoglobin from plasma monitored by radioimmunoassay. A monoexponential regression line (corresponding to a one-compartment model) and a biexponential regression line (corresponding to a two-compartment model) were determined for each set of washout data, the kinetic parameters were calculated, and the goodness of fit of each model was assessed. Results were similar after both methods of myoglobin administration. In five of 11 animals, the one-compartment model described the myoglobin kinetics better; in the other six animals, the two-compartment model was statistically superior, but values for the volume of distribution and elimination rate constant differed by only 10% from the one-compartment estimates. After bolus administration of myoglobin and with a one-compartment model, the volume of distribution of myoglobin was determined to be 1,601 +/- 77 (SEM) ml, representing 6.8 +/- 0.2% of total body weight; the elimination rate constant averaged 0.132 +/- 0.006/min and corresponded to a mean half-time of disappearance of 5.5 +/- 0.2 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Quantitation of myoglobin saturation in the perfused heart using myoglobin as an optical inner filter.

Quantitation of metabolic parameters using the technique of cardiac surface fluorescence is complicated by motion and changes in tissue absorption. Because ratio fluorescence methodology can be applied to eliminate motion-induced errors, in the current study, we used a ratio fluorescence technique to evaluate myoglobin saturation in the perfused rat heart, since myoglobin is the major oxygen-dependent light absorbing species in this tissue. Changes in myoglobin saturation can affect surface fluorescence measurements as a result of the inner filter effect. Optical scans of heart extracts indicated the major absorption peak is due to myoglobin and its peak wavelength shifts from 415 to 430 nm upon deoxygenation. To monitor this shift in hearts, the isolated perfused heart was loaded covalently with the fluorescent dye 7-diethylaminocoumarin-3-carboxylic acid by brief perfusion with the succinimidyl ester. This dye has an excitation maximum in the region of maximal absorption by myoglobin and allows for monitoring myoglobin oxygenation using the inner filter effect. The dye localized to endothelial cells and increased the surface fluorescence in this wavelength region approximately 50-fold above background levels without affecting cardiac function. An equation was derived to estimate the fraction of myoglobin in the oxygenated state from changes in the fluorescence 415/430 excitation ratio. From this fraction, the average PO2 in the environment of myoglobin was estimated under several perfusion conditions. We report that retrograde perfusion in the Langendorff mode at either 60 or 120 mmHg pressure resulted in full oxygenation of myoglobin with use of cell-free perfusate equilibrated with 95% O2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Dynamics of changes in the levels of myoglobin and anti-myoglobin autoantibodies in the blood serum of patients with myocardial infarction].

The mean level of myoglobin and autoantibodies to myoglobin in the blood of healthy donors was 77.57 +/- 8.17 ng/ml and 18.01 +/- 1.85 micrograms/ml respectively. The level of myoglobin in the blood of patients with primary transmural myocardial infarction was rapidly increased, reaching its maximum in 9-12 h and returning to normal in 9 days. The mean level of autoantibodies was decreased in the first 66 h and got back to normal by the 6th day of disease. In primary large focal nontransmural myocardial infarction the concentration of myoglobin in the blood of patients was also increased, reaching its maximum in 3-9 h and returning to normal by the end of the 2nd day after onset of an angina attack. A decrease in the level of autoantibodies to myoglobin was observed up to the 18th day of disease. The peculiarity of repeated large focal nontransmural myocardial infarction was a two-peak curve of changes in a MG level with maximum levels in 9-12 and 21-24 h after onset of a pain attack. Final normalization of the level of myoglobin in the blood of patients of this group occurred in 69 h. The concentration of autoantibodies to myoglobin was more than once decreased up to the 6th day of disease. The results obtained showed that groups of examinees differed in the time course of changes in the level of myoglobin and autoantibodies to myoglobin. Such differences can be used for diagnostic purposes.

Autoantibodies↗
PubMed1966

Studies on myoglobin from the finback whale (Balaenoptera physalus). Preparation, physicochemical and immunochemical characterization, differentiation from sperm-whale myoglobin, amino acid composition and end-terminal analyses.

1. Crystalline myoglobin was isolated from the skeletal muscle of the finback whale and fractionated, in its cyanmet form, into nine components (I-IX) by chromatography on CM-cellulose. Also in the cyanmet form, it was resolved into six components by electrophoresis on starch gel. Correspondence between the electrophoretic and chromatographic components was determined, and interconversion between components revealed by chromatography and electrophoresis. 2. The chromatographic myoglobin components were homogeneous in the ultra-centrifuge. Molecular weights of certain components were determined by means of sedimentation equilibrium and by gel filtration on Sephadex G-100. Values from these two methods corresponded to the minimum molecular weight calculated from the iron content. 3. The spectral properties of the chromatographic components were investigated in the visible and the ultraviolet ranges. 4. The major components of finback-whale myoglobin and sperm-whale myoglobin showed almost identical spectral, electrophoretic and chromatographic behaviours, but had different infrared spectra. The infrared spectra of the corresponding apoproteins were almost identical. 5. Rabbit antisera to sperm-whale myoglobin component X cross-reacted with finback-whale myoglobin components V, VI and VII only about 30%. 6. The major chromatographic components of finback-whale myoglobin have identical amino acid compositions. The polypeptide chain contains 151 amino acid residues and its molecular weight is 17504. 7. The N-terminal end of the chain is: [Formula: see text] Amino acids released from myoglobin by the action of carboxypeptidase A at different intervals were determined.

Amino Acids↗
PubMed1980

Myoglobins of cartilaginous fishes. II. Isolation and amino acid sequence of myoglobin of the shark Mustelus antarcticus.

Myoglobin isolated from red muscle of the gummy shark M. antarcticus was purified by gel filtration and ion-exchange chromatography on carboxymethyl cellulose in 8 M urea-thiol buffer. Amino acid analysis and sequence determination showed 148 amino acid residues. The amino terminal residue is acetylated as shown by nuclear magnetic resonance and mass spectrographic analysis of an N-terminal peptide. There is a deletion of four residues at the amino terminal end as well as one residue in the CD interhelical area relative to other myoglobins. These overall differences were also found previously in myoglobin of Heterodontus portusjacksoni. The complete amino acid sequence has been determined following digestion with trypsin, chymotrypsin, thermolysin, staphylococcal protease and cyanogen bromide. Sequences of purified peptides were determined by the dansyl-Edman procedure. The amino acid sequence showed approximately 88 differences from mammalian, monotreme, bird and tuna myoglobins, slightly more than previously reported for H. portusjacksoni usually considered a more primitive animal. There were 24 residues common to both shark myoglobins that were different from those present in other myoglobins. The sequence has been compared to the myoglobin of yellowfin tuna and other myoglobins.

Amino Acid Sequence↗
PubMed1994

Immunoassays for serum and urine myoglobin: myoglobin clearance assessed as a risk factor for acute renal failure.

We compared four immunoassays for serum and urine myoglobin. Within-run CVs were 5-13%, with biases seen between assays. Myoglobin was stable for 1 month in serum and 12 days in urine when the pH was adjusted to between 8.0 and 9.5. Hemoglobin caused no interference. We assayed 91 pairs of serum and timed urine specimens from 41 patients admitted for acute trauma or rhabdomyolysis. Most were treated with mannitol and alkalinization. Upon initial presentations, 21 patients with either low serum myoglobin concentrations (< 400 micrograms/L) or high myoglobin clearances (> or = 4 mL/min) had normal creatinine clearances and no clinical evidence of renal disease. The remaining 20 had low myoglobin clearances. Seven were in rhabdomyolysis-induced acute renal failure, or subsequently developed this complication. We suggest that low myoglobin clearance may indicate a high risk for developing renal failure or may be an early marker for kidney dysfunction. Low myoglobin clearance may prove useful in indicating failure of prophylactic treatment to clear myoglobin.

Acute Kidney Injury↗
PubMed1994

Abalone myoglobins evolved from indoleamine dioxygenase: the cDNA-derived amino acid sequence of myoglobin from Nordotis madaka.

The cDNA for the unusual 41 kD myoglobin of the abalone Nordotis madaka was amplified by polymerase chain reaction (PCR), and the cDNA-derived amino acid sequence of 378 residues was determined. As with the myoglobin of the related abalone Sulculus diversicolor (Suzuki and Takagi, J. Mol. Biol. 228, 698-700, 1992), the sequence of Nordotis myoglobin showed no significant homology with any other globins, but showed high homology (35% identity) with vertebrate indoleamine 2,3-dioxygenase, a tryptophan degrading enzyme containing heme. The amino acid sequence homology between Nordotis and Sulculus myoglobins was 87%. These results support our previous idea that the abalone myoglobins evolved from a gene for indoleamine dioxygenase, but not from a globin gene, and therefore all of the hemoglobins ard myoglobins are not homologous. Thus, abalone myoglobins appear to be a typical case of convergent evolution.

Amino Acid Sequence↗
PubMed1995

Interactions among residues CD3, E7, E10, and E11 in myoglobins: attempts to simulate the ligand-binding properties of Aplysia myoglobin.

Site-directed mutations have been introduced singly and in combination at residues lysine/arginine45 (CD3), histidine64 (E7), threonine67 (E10), and valine68 (E11) in pig and sperm whale myoglobins. The mutations probe the roles of these key distal pocket residues and represent attempts to mimic the heme environment of Aplysia limacina myoglobin which achieves moderately high O2 affinity in the absence of a distal histidine. In the mollusc myoglobin, arginine-E10 is believed to swing into the heme pocket and provide a hydrogen bond to the bound O2. The association and dissociation rate constants for oxygen and carbon monoxide binding to H64V, T67A, T67V, T67E, T67R, V68I, V68T, H64V-T67R, H64V-V68T, H64V-V68I, and H64V-T67R-V68I pig myoglobin mutants and T67R, H64V-T67R, and R45D-H64V-T67R mutants of sperm whale myoglobin have been measured using stopped-flow rapid mixing and flash photolysis techniques. Replacement of histidine-E7 with valine in either pig or sperm whale myoglobin drastically lowers O2 affinity while increasing CO affinity. Two second-site mutations, T67R and V68T, increase O2 affinity in the H64V mutant, even though when introduced singly these mutations have no effect or lower KO2, respectively. However, the oxygen affinities of the H64V-T67R mutants are 5-10-fold lower than that of A. limacina myoglobin. The crystal structure of the pig H64V-T67R double mutant reveals that the valine-E7 side chain is approximately 1 A closer to the heme plane than in the mollusc protein which may restrict access of the arginine-E10 side chain into the heme pocket. The O2 affinity of the H64V-T67R double mutant is not altered by the R45D replacement but is reduced 10-fold by the V68I mutation. The interactive effects of the T67R, V68I, and V68T mutations with the H64V substitution are discussed in terms of O2, CO, and N3-binding and the crystal structures of the H64V-T67R, H64V-V68I, and H64V-V68T double-mutant proteins. In many instances, the effects of second-site mutations in the valine64 background are the opposite of those observed for the corresponding single mutations in the wild type background. These results can be understood in terms of the changes in the rate-determining steps for ligand association and dissociation and the loss of distal pocket water molecules which follow replacement of histidine64 by valine.

Amino Acid Sequence↗
PubMed1986

Crystal structures of modified myoglobins. II. Relation between oxygen affinity properties and structural changes around heme in myoglobins reconstituted with 2,4-diisopropyldeuteroheme, 2-isopropyl-4-vinyldeuteroheme, and 2-vinyl-4-isopropyldeuteroheme.

The crystal structures of sperm whale metmyoglobins reconstituted with three kinds of modified hemes, 2,4-diisopropyldeuteroheme, 2-isopropyl-4-vinyldeuteroheme, and 2-vinyl-4-isopropyldeuteroheme, have been determined and refined at 2.2 A resolution to R = 0.216, 0.219, and 0.195, respectively. All the crystals of these myoglobins are isomorphous with that of native metmyoglobin. The 2-vinyl-4-isopropyldeuteroheme was found to be in a reverse orientation, in which the heme plane is rotated by 180 degrees about an axis through the alpha-gamma-meso carbons, whereas the orientations of the other two hemes were the same as that of protoheme in native myoglobin. In the myoglobins with 2,4-diisopropyldeuteroheme and 2-vinyl-4-isopropyldeuteroheme, both of which have lower oxygen affinities than native myoglobin, the bulky isopropyl side chain pushes Phe 43 0.7 A toward His 64 (the distal histidine) in the former, and the whole E helix at most 1.5 A, including a 0.7 A shift of the His 64 imidazole ring, in the latter. The changes of the structures prevent His 64 from forming a hydrogen bond with the liganded oxygen molecule, so that these two modified myoglobins show low oxygen affinities. On the other hand, there is no such drastic displacement in myoglobin with 2-isopropyl-4-vinyldeuteroheme, which has a slightly higher oxygen affinity than native myoglobin.

Animals↗
PubMed1981

Myoglobins of cartilaginous fishes III. Amino acid sequence of myoglobin of the shark Galeorhinus australis.

Myoglobin isolated from the red muscle of the school shark Galeorhinus australis was purified by gel filtration and ion-exchange chromatography. The amino acid sequence was determined following digestion with trypsin and purification of the peptides by paper ionophoresis and chromatography. Sequences of purified peptides were determined by the dansyl-Edman procedure and the peptides aligned by homology with the sequence of the myoglobin of the gummy shark Mustelus antarcticus. The two myoglobin sequences showed a marked similarity (16 differences), but both sequences showed approximately the same number of differences (68) from myoglobin of the Port Jackson shark Heterodontus portusjacksoni. There are 19 residues unique to three shark myoglobin sequences. As found with other fish myoglobins there are 148 residues with deletions of four residues at the amino terminal end as well as one residue in the CD region. The amino terminal residue is acetylated. The distal E7 histidine residue was found to be replaced by glutamine, as only previously reported for the myoglobin sequence of gummy shark.

Amino Acid Sequence↗