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At least 19 recordsLinked to original sources
PubMed1977

Myoglobin as an oxygen indicator for measuring the oxygen binding characteristics of a modified myoglobin derivative containing covalently bound mesoheme.

By measuring the visible spectrum of a mixture of myoglobin and a modified derivative containing mesoheme in place of the normal protoheme, it is possible to evaluate the relative amounts of the oxidized, reduced, and oxygenated forms of each type of myoglobin. If the oxygen affinity of one myoglobin derivative is known, the oxygen affinity of the other can be determined from measurements at various oxygen partial pressures. In the absence of excess reducing agent, the rate of autoxidation can also be evaluated during the same experiment. The method described is suitable at very low oxygen partial pressures, where most previous methods are inaccurate, and it is very convenient to use, since no time-consuming calibration procedures are required. Using protoheme myoglobin as an oxygen indicator, the oxygen pressure at half saturation (P 1/2) of mesoheme myoglobin was shown to be 11% higher than the P 1/2 of a modified myoglobin derivative containing covalently bound mesoheme. The autoxidation rate of the covalent derivative is faster than that of the noncovalent derivative, but it is less dependent on oxygen pressure.

Chemical Phenomena↗
PubMed1977

Studies on cobalt myoglobins and hemoglobins. Interaction of sperm whale myoglobin and Glycera hemoglobin with molecular oxygen.

The pH dependence of the electron paramagnetic resonance (EPR) spectrum and oxygen affinity of cobaltous porphyrin-containing myoglobin (CoMb) have been examined. The hyperfine structures of the EPR spectrum of oxy-CoMb undergo small, reversible pH-dependent changes with pK values of 5.33, 5.55, and 5.25 +/- 0.05 for proto-, meso-, and deutero-CoMb's, respectively, whereas deoxy-CoMb does not exhibit any pH dependence of its EPR spectrum. The partial pressure of oxygen at half-saturation of proto-CoMb decreases from 26 to 42 Torr on lowering the pH from 7.0 to 4.8. For comparison, we have prepared cobaltous porphyrin-containing monomeric Glycera hemoglobin (CoHb (Glycera)), in which the distal histidyl group of myoglobin is replaced by a leucyl residue, and examined the equilibria and kinetics of its oxygenation and EPR spectrum. CoHb (Glycera) has exhibited a very low oxygen affinity (p50 = 7 X 10(2) Torr at 5 degrees) and a large dissociation rate constant (more than 8 X 10(4) S-1 at 5 degrees). The EPR spectrum of oxy-CoHb (Glycera) was affected by neither pH nor replacement of H2O with D2O. Low temperature photodissociation studies by EPR and spectrophotometry have shown that the photolyzed form of the ligated hemoglobin (Glycera) is similar to its deoxy form, in contrast to myoglobin which gives a new intermediate states as the photolyzed form. These differences between CoMb and CoHb (Glycera) are interpreted with relation to the possible role of the distal histidyl residue in CoMb.

Animals↗
PubMed1975

Electrostatic effects in myoglobin. Application of the modified Tanford-Kirkwood theory to myoglobins from horse, California grey whale, harbor seal, and California sea lion.

The modified Tanford-Kirkwood electrostatic theory (Shire et al., 1974a) was applied to ferrimyoglobins from the following animal species: sperm whale (Physeter catodon), horse, California grey whale (Eschrichtius gibbosus), harbor seal (Phoca vitulina), and California sea lion (Zalophus californianus). Computations were made of the overall hydrogen ion titration curves of the proteins, and of pH and ionic strength variations of ionization equilibria for individual groups in the protein, with particular reference to the hemic acid ionization of the iron bound water molecule. Coordinates and static solvent accessibility were estimated in terms of the sperm whale myoglobin structure. Where possible, theoretical results and experimental data are compared. Some comparative features of charge and ionization properties among the various myoglobins are presented.

Amino Acids↗
PubMed1979

[A study on the physiological basis of training effect--with special reference to myoglobin. I. Isolation and properties of myoglobin from dog skeletal muscle (author's transl)].

Myoglobin (Mb) was isolated from canine skeletal muscle by a novel heat denaturation-gel filtration-ion exchange chromatography procedure. The purified major Mb was homogeneous by gel electrophoretic and ultracentrifugal analysis, and the sedimentation coefficient at infinite dilution (S degrees 20, w) was 1.9 S. The molecular weight by sedimentation equilibrium was 1.72 X 10(4) and was essentially identical with the values by the iron analysis (1.80 X 10(4) and the amino acid composition (1.78 X 10(4). The spectroscopic properties of deoxy-, oxy-, carbonmonoxy- and met-derivatives of the Mb were determined in ultraviolet, Soret and visible regions. The pK' of acid-alkaline transition of the met-Mb was estimated as 8.80+/-0.04 (25 degrees) from the pH-dependent spectral change. The oxygen equilibrium studies revealed complete absence of such allosteric properties as heme-heme interaction, anion effect and the Bohr effect which were always present in normal mammalian hemoglobins. Oxygen tension for the half-oxygenation was 0.48 mmHg (20 degrees) and its temperature-dependent change gave the delta H degrees of -15.7 Kcal/mole.

Amino Acids↗
PubMed1979

Preparation of ruthenium(II) and ruthenium(III) myoglobin and the reaction of dioxygen, and carbon monoxide, with ruthenium(II) myoglobin.

Ruthenium myoglobins have been prepared by the reconstitution of horse heart apomyoglobin with either ruthenium(II) or ruthenium(III) mesoporphyrin IX (MpIX) derivatives. The ruthenium(II) and -(III) myo globins (RuMb and RuMb+, respectively) contain one ruthenium porphyrin/heme binding site; the species are readily interconverted using dithionite for reduction and bromine for oxidation. RuMb binds carbon monoxide to give the known carbonyl complex. Reversible oxygenation occurs readily with protein-free RuII(MpIX) species in dimethylformamide, but RuMb in phosphate buffer is irreversibly oxidized by dioxygen to give RuMb+ via an outer sphere electron transfer mechanism.

Animals↗
PubMed1979

Radioimmunoassays of human myoglobin in serum and urine.

Two solid-phase radioimmunoassays have been developed for the detection of myoglobin in serum and urine. The sensitivity of the methods is 0.1 and 0.5 microgram/l, respectively, with a coefficient of variation of the respective method of 7-8%. The mean serum concentration of myoglobin in ninety-nine healthy blood donors was 44.3 microgram/l +/- 18.0 microgram/l (SD) with a significant difference (P less than 0.001) between men (50.6 +/- 19.8) and women (35.7 +/- 10.4). Serum myoglobin was positively correlated to age (P less than 0.05), body weight (P less than 0.02), serum creatine kinase (P less than 0.001), and serum creatinine (P less than 0.001) to galactose elimination rate. Serum myoglobin levels were not influenced by exhaustive short time dynamic exercise. The mean urinary excretion of myoglobin in twenty-four healthy students was 1.2 microgram/24 h (range 0.1-4 microgram/24 h). Myoglobin excretion was correlated to excretion of beta 2-microglobulin (P less than 0.02) but not to serum levels of myoglobin. No indications of circulating antibodies to myoglobin were obtained when assaying sixty-seven rheumatoid arthritis and thirteen myastenia gravis sera. Presence of other myoglobin binding substances in serum, which would interfere with the assays also seemed unlikely. Determination of myoglobin in serum by sensitive and specific method might be of clinical value in the diagnosis of diseases involving muscle tissues.

Adult↗
PubMed1978

Myoglobin turnover--influence of renal and extrarenal factors.

The serum level of myoglobin, an LMW constituent of striated and myocardial muscle, has been studied in various clinical situations in order to obtain information about factors influencing myoglobin turnover. The myoglobin level was significantly correlated to different variables of GFR such as serum beta2-microglobulin, serum creatinine, and 51Cr-EDTA clearance. Following a successful renal transplantation rapid decrease in serum myoglobin was found parallel to increase in GFR's. In patients with advanced long-standing uremia, comparatively small elevations of serum myoglobin were seen when correlated to the degree of GFR reduction, demonstrating an influence of extrarenal factors on the myoglobin levels. The importance of extrarenal factors on the actual serum level of LMW proteins was also illustrated by serial studies on SLE patients receiving corticosteroid therapy. In these patients, elevations of serum myoglobin levels were found, but serum beta2-microglobulin levels gradually decreased during therapy. Finally, calculations based on curves of serum disappearance of myoglobin in patients with acute myocardial infarction indicate that only about 0.3 mg of myoglobin per day is released from the muscle pool during normal conditions, which suggests that myoglobin catabolism mainly occurs within the muscle tissue.

Adolescent↗
PubMed1977

Serum myoglobin in myocardial infarction: the "staccato phenomenon." Is acute myocardial infarction in man an intermittent event?

When serum was sampled frequently and soon after acute myocardial infarction, myoglobinemia was extremely common, occurring in 12 of 13 selected patients. Myoglobin first appeared in the serum within a few hours after infarction, but not consistently earlier than creatine phosphokinase. The peak level of serum myoglobin was reached appreciably earlier than the peak values of serum creatine phosphokinase activity. Time of earliest myoglobin appearance in the serum, peak level of myoglobin measured, and duration of detectable myoglobin release all correlated poorly with clinical and biochemical estimates of severity of myocardial infarction. There was no correlation between myoglobin levels and infarct size as estimated from creatine phosphokinase kinetics. Myoglobin appeared in the serum in multiple short "staccato" bursts, or episodes, often lasting only one to two hours. The hypothesis is suggested that the pattern of myoglobin appearance is a reflection of the episodic nature of acute myocardial infarction. Although isolated myoglobin determination may not be useful at present, for quantification of total myocardial damage, its pattern of release may be a sensitive marker for studying the time course of infarction, and may be useful to evaluate therapeutic interventions designed to interrupt an ongoing syndrome of myocardial necrosis.

Acute Disease↗
PubMed1978

Oxygenation and EPR spectral properties of Aplysia myoglobins containing cobaltous porphyrins.

Cobalt myoglobins (Aplysia) have been reconstituted from apo-myoglobin (Aplysia) and proto-, meso-, and deutero-cobalt porphyrins. Each of them showed the 30--60 times lower oxygen affinity than those of the corresponding cobalt myoglobins (Sperm whale). Kinetic investigation of their oxygenation by the temperature-junp relaxation technique showed that the low oxygen affinity of cobalt myoglobin (Aplysia) is due to a large dissociation rate constant. the electron paramagnetic resonance (EPR) spectrum of oxy cobalt myoglobin (Aplysia) is affected by the replacement of H2O with D2O, suggesting a possible interaction between the bound oxygen and the neighboring hydrogen atom. A low temperature photodissociation study showed that the product of photolysis of oxy cobalt myoglobin (Aplysia) gives an EPR spectrum different from that of the deoxy-cobalt myoglobin (Aplysia) and from that of the photolysed form of oxy-cobalt myogloin (Sperm whale). These observations suggest that in oxy-cobalt myoglobin (Aplysia) the bound oxygen might interact with amino acid adjacent to it, but the interaction is weaker than that in oxy cobalt myoglobin (Sperm whale).

Animals↗
PubMed1977

Antibodies against protein antigenic sites that are identical in the homologous protein of the immunized animal. Autoreactivity in rabbits of antibodies to sperm-whale myoglobin.

Sequence comparisons between the antigenic sites of sperm-whale myoglobin and the corresponding regions in rabbit myoglobin indicate that rabbits make antibodies to regions of the sperm-whale myoglobin molecule which are identical to the corresponding regions in rabbit myoglobin. Rabbit myoglobin did not precipitate with antisera to sperm-whale myoglobin. However, it exhibited an extensive cross-reaction as demonstrated by its ability to inhibit the precipitin reaction of sperm-whale myoglobin, and on an immunoadsorbent, bound a large amount of antibodies to sperm-whale myoglobin.

Amino Acid Sequence↗
PubMed1975

Studies on the charge transfer band in high spin state of ferric myoglobin and hemoglobin by low temperature optical and magnetic circular dichroism spectroscopy.

The behavior of charge transfer band, appearing at 600-650 nm in ferric high spin derivatives of myoglobin and hemoglobin, was studied under various conditions by low temperature optical and magnetic circular dichroism spectroscopy. Optical absorption spectra have demonstrated that: (1) The charge transfer band at 630 nm of myoglobin (Fe3+)-H2O (pH 7.0) at room temperature split into three bands, 627 nm, 645 nm and 664 nm (shoulder) at 77 degrees K, whereas that of hemoglobin (Fe3+)-H2O showed no splitting. (2) By lowering the pH value from 7.5 to 4.3 this splitting in myoglobin was observed to disappear only in the presence of a small amount of phosphate ion, accompanying a midpoint at pH 6.7 +/- 0.1. This does not originate from the released hemin. (3) Hemin (pH 7.55) showed no splitting of the charge transfer band at 77 degrees K. (4) This splitting depended on the species of 6th ligand. For myoglobin-F- the splitting could scarcely be observed, whereas the proton-donating ligands such as HCOOH and CH3OH exhibit the splitting as well as H2O. Magnetic circular dichroism spectra have demonstrated that: (5) The charge transfer band at 600-500 nm indicated Faraday A term and B term. (6) A negative B term band was observed at 650 nm for myoglobin-H2O in the glassic solvent of potassium glycerophosphate-glycerol, whereas it was not observed for hemoglobin-H2O. Several discussions were performed on the origin of splitting of the charge transfer band in myoglobin-H2O. It is now concluded that the hydrogen bond between the 6th ligand and the distal histidine contributes to the splitting of the charge transfer band around 630 nm for myoglobin Fe3+)-H2O at low temperature and that disappearance of the splitting at low pH is originated from the presence of phosphate ion.

Adult↗