Showing papers on "Myoglobin published in 1973"
TL;DR: The oxygen equilibrium and the absorbance spectrum of the oxygenated form were successfully measured with myoglobin and hemoglobins A and M Boston and it was found that the addition of catalase or peroxidase was required for the complete reduction of metmyoglobin.
324 citations
TL;DR: The findings indicate that myoglobin molecules cross the endothelium of muscle capillaries primarily via plasmalemmal vesicles, and suggest that the same structures are, at least in part, the structural equivalent of the small pore system of this type of capillary.
Abstract: Whale skeletal muscle myoglobin (mol wt 17,800; molecular dimensions 25 x 34 x 42 A) was used as a probe molecule for the pore systems of muscle capillaries. Diaphragms of Wistar-Furth rats were fixed in situ at intervals up to 4 h after the intravenous injection of the tracer, and myoglobin was localized in the tissue by a peroxidase reaction. Gel filtration of plasma samples proved that myoglobin molecules remained in circulation in native monomeric form. At 30–35 s postinjection, the tracer marked ∼75% of the plasmalemmal vesicles on the blood front of the endothelium, 15% of those located inside and none of those on the tissue front. At 45 s, the labeling of vesicles in the inner group reached 60% but remained nil for those on the tissue front. Marked vesicles appeared on the latter past 45 s and their frequency increased to ∼80% by 60–75 s, concomitantly with the appearance of myoglobin in the pericapillary spaces. Significant regional heterogeneity in initial labeling was found in the different segments of the endothelium (i.e., perinuclear cytoplasm, organelle region, cell periphery, and parajunctional zone). Up to 60 s, the intercellular junctions and spaces of the endothelium were free of myoglobin reaction product; thereafter, the latter was detected in the distal part of the intercellular spaces in concentration generally equal to or lower than that prevailing in the adjacent pericapillary space. The findings indicate that myoglobin molecules cross the endothelium of muscle capillaries primarily via plasmalemmal vesicles. Since a molecule of this size is supposed to exit through both pore systems, our results confirm the earlier conclusion that the plasmalemmal vesicles represent the large pore system; in addition, they suggest that the same structures are, at least in part, the structural equivalent of the small pore system of this type of capillaries.
188 citations
TL;DR: Estimation of mean myoglobin oxygen tension was applied from measurements of carbon monoxide binding to myoglobin to the in vivo canine myocardium, and evidence was obtained that it occurred at a time during acute progressive hypoxemia when intracellular oxygen tensions limited aerobic metabolism.
Abstract: COBURN, R. F., F. PLOEGMAKERS, P. GONDRIE, AND R. ABBOUD. Myocardial myoglobin oxygen tension. Am. J. Physiol. 224(4): 870-876. 1973.-We have applied our method of estimating mean myoglobin oxygen tension from measurements of carbon monoxide binding to myoglobin to the in vivo canine myocardium. Carbon monoxide binding to myoglobin was determined with measurements of 14C0 in myocardial biopsy specimens. The quantity of carbon monoxide bound to myoglobin, expressed as a ratio of carboxymyoglobin to carboxyhemoglobin, remained constant over a wide range of arterial oxygen tensions, above 30-35 mm Hg. Mean myoglobin oxygen tensions at normal arterial oxygen tensions were computed to be 4-6 mm Hg. Fine control of intracellular oxygen tension was demonstrated, since only small changes in mean myoglobin oxygen tension occurred with large changes in arterial oxygen tension, as long as arterial oxygen tensions remained greater than 30-35 mm Hg. With acute progressive hypoxemia, influx of carbon monoxide into myocardium occurred at a time when arterial oxygen tension fell to less than 30-35 mm Hg. This influx is thought to be due to a fall in intracellular oxygen tension, and evidence was obtained that it occurred at a time during acute progressive hypoxemia when intracellular oxygen tensions limited aerobic metabolism.
94 citations
TL;DR: Rebinding of carbon monoxide to myoglobin and to cytochrome P-450 after removal by a light flash occurs down to 50�K for myoglobin in glycerol-water solution.
Abstract: Rebinding of carbon monoxide to myoglobin and to cytochrome P-450 after removal by a light flash occurs down to 50 degrees K for myoglobin and 25 degrees K for cytochrome P-450 in glycerol-water solution. Above 240 degrees K the reaction is second order; between 240 degrees and 200 degrees K the rebinding becomes exponential and independent of the carbon monoxide concentration. Below 150 degrees K the reaction follows a power law and is approximately 10(3) times faster for cytochrome P-450 than for myoglobin.
71 citations
TL;DR: These results suggest that the principal factors governing reversible oxygen binding are the electronic nature of the base (imidazole), neighboring-group effects of the basic group, and immobilization of the heme group.
Abstract: A simple heme-imidazole compound, having the same geometry as the heme-imidazole complex in myoglobin, has been synthesized. This compound, ferropyrroporphyrin-N-[3-(1-imidazolyl)propyl]amide, reversibly binds oxygen in the solid state or when dissolved in a polystyrene film. These results suggest that the principal factors governing reversible oxygen binding are the electronic nature of the base (imidazole), neighboring-group effects of the basic group, and immobilization of the heme group.
68 citations
TL;DR: Some results on myoglobin and hemoglobin are presented, which show changes in the structure or in the conformation of the heme and its environment are expected to show up in a change in the endor spectrum.
Abstract: Heme proteins play a vital role in many biological processes: the storage of oxygen (myoglobin) , the transport of oxygen (hemoglobin), the shuttling of electrons (cytochromes) and enzymatic reactions (e.g., peroxidases) , to name a few. Many different techniques have been used in the past to elucidate the structure of heme proteins. These include x-ray diffraction, optical spectroscopy, Mossbauer spectroscopy, high resolution nuclear magnetic resonance (nmr) and electron paramagnetic resonance (epr) spectroscopy. Within the past year we have started a program to investigate heme proteins by the electron nuclear double resonance (endor) technique. In this paper we present some results on myoglobin and hemoglobin. Some of these are still preliminary in nature and should therefore be taken in the spirit of a progress report. What can endor do that hasn’t been already done by the other techniques? It can determine, with a high degree of precision, the interactions of the paramagnetic ion, in our case the iron (Fe+++) of the heme, with its surrounding nuclei. From the value of these interactions one may obtain the electron cloud distribution (i.e., the square of the electronic wave functions) at the nuclei, the distance of the iron to the nuclei and the electric field gradient at the nuclei, in short, the intimate electronic details of the iron and its environment. Since the iron represents the “business end” of the molecule, such detailed information should lead to a more complete, quantum mechanical understanding of the relationship between electronic structure and function. Changes in the structure or in the conformation of the heme and its environment are also expected to show up in a change in the endor spectrum. A problem of central interest in which such changes play a major role is the cooperative oxygenation effect in hemoglobin.
47 citations
TL;DR: Reynafarje's (1963) spectrophotometric method was modified for the study of myoglobin concentration in rat hearts and a severe cardiomegaly developed which was most pronounced in the right ventricle.
Abstract: Reynafarje's (1963) spectrophotometric method was modified for the study of myoglobin concentration in rat hearts. The influence of age and body weight was evaluated and the age was found to be better correlated with myoglobin concentration than the weight. The influence of simulated altitude of 3500 m was studied in animals exposed to hypoxia at the age of about 34 days and in animals born in the low pressure chamber. In the first group a higher myoglobin concentration was found but only in the right ventricle, together with unilateral hypertrophy, as compared with control animals. In the group of animals born at simulated altitude a severe cardiomegaly developed which was most pronounced in the right ventricle. The myoglobin concentration in the hearts from this group was unchanged in the right ventricle and was lower in the left ventricle and septum.
37 citations
Journal Article•
TL;DR: A model is proposed in which the acid and alkaline conformers of the ligand-free protein have differentligand-binding properties and it is suggested that there is a pH-dependent transition in the CO adduct of Cm-cytochrome c and the pK of this transition is reported.
36 citations
TL;DR: X-ray small-angle scattering of myoglobin in aqueous solutions enhances the probability that the structure of the myoglobin is conserved on passing to the dissolved state.
36 citations
Journal Article•
TL;DR: The effect of pH and certain additives on the denaturation of various turkey myoglobins was studied in a model system as mentioned in this paper, and the effect of the myoglobin derivative appeared to have an effect on the amount of pigment denatured by temperature in a crude myoglobin extract.
TL;DR: The volume effects associated with the various transitions are the summation of such processes as the change of the partial molar volume of theprotein, normalizing of masked ionic groups, electrostriction effects, and other less well defined phenomena arising from the alteration of the protein.
TL;DR: In leg muscle cultures a rapidly increasing amino acid incorporation into myoglobin begins two days after muscle cell fusion; in breast muscle cultures no comparable increase was observed.
Abstract: Myoglobin synthesis was compared in cell cultures of leg (red) and breast (white) muscle of chick embryos. In leg muscle cultures a rapidly increasing amino acid incorporation into myoglobin begins two days after muscle cell fusion; in breast muscle cultures no comparable increase was observed. This qualitative difference in cultures of the two muscle cell types provides possibilities for the further study of the mechanism of myoglobin synthesis.
TL;DR: The skeletal muscle myoglobin of the water buffalo has been purified by a rapid and simplified procedure and the amino acid composition of the myoglobin has been determined.
Abstract: 1. 1. The skeletal muscle myoglobin of the water buffalo ( Bos bubalus L.) has been purified by a rapid and simplified procedure. 2. 2. The amino acid composition of the myoglobin has been determined. 3. 3. The N -terminal amino acid is glycine. 4. 4. The results have been compared with other mammalian myoglobins, particularly that of the cow.
TL;DR: Purified deoxygenated sperm whale myoglobin solutions were exposed to gamma irradiation at levels up to 500 krad and Binding studies with n- butyl isocyanide suggested that irradiated myoglobin exhibits less steric hindrance than does control protein.
Abstract: Purified deoxygenated sperm whale myoglobin solutions were exposed to gamma irradiation at levels up to 500 krad. Following irradiation the solutions could be resolved by Sephadex chromatography into three fractions: monomer (molecular weight, M. W., estimate 17,000); dimer (M. W. 38,000); and polymers (M. W. 60,000 and greater). Dimer formation appeared to be intermediate to production of polymer fractions. All three fractions had the same spectral characteristics. Liganded derivatives of all three were less susceptible to change manifested by a lower Soret (409 nm) to protein (280 nm) absorbance ratio than was nonliganded metmyoglobin. The presence of excess ligand inhibited dimer and polymer formation, presumably due to the fact that such ligands may act as free radical scavengers. Irradiated myoglobin preparations showed many new bands on electrofocusing, underwent autoxidation at faster rates than controls, and were more susceptible to acid and thermal denaturation. Binding studies with n- butyl isocyanide suggested that irradiated myoglobin exhibits less steric hindrance than does control protein. (auth)
Journal Article•
Journal Article•
TL;DR: In this paper, small conformational changes in a molecule of sperm-whale myoglobin in its native solid state for different pH values at room temperature as well as during heat denaturation in alkali medium at different stages of unfolding of the globule were observed by using far-infrared spectroscopy in the region from 30 to 600 cm−1.
Abstract: Small conformational changes in a molecule of sperm-whale myoglobin in its native solid state for different pH values at room temperature as well as during heat denaturation in alkali medium at different stages of unfolding of the globule were observed by using far-infrared spectroscopy in the region from 30 to 600 cm−1. The changes appeared in the absorption bands near 420 and 470 cm−1 ascribed to the side-chain vibrations of helical segments of the myoglobin molecule. For the first time the high structural sensitivity of the far-infrared region of the skeletal vibrations has been confirmed experimentally and the applicability of this technique to globular proteins demonstrated.
TL;DR: The great variation of values is interpreted as an inhomogeneous distribution of the local myoglobin concentration in hemoglobin-free perfused guinea-pig heart.
Abstract: A method is described for calculating local myoglobin concentration in hemoglobin-free perfused guinea-pig heart by measuring the decrease of tissuePo2 during stop of perfusion. The myoglobin concentration in ca. 10 nanogram of tissue varies between 0.106 and 0.676 g-% of the wet weight. The mean value of 0.373 g-% (standard deviation of ±0.138) agrees very well with the values obtained with chemical methods by other authors. The great variation of our values is interpreted as an inhomogeneous distribution of the local myoglobin concentration.
TL;DR: A comparison of the sarcoplasmic proteins of white and red muscle by starch-gel electrophoresis revealed that the differentiation observed in the coelacanth was similar to that occurring in the carp, and a study of the low-molecular-weight proteins, or parvalbumins, of white muscle and of the myofibrillar proteins shows the expected differences between the two muscle types.
Abstract: Although the anatomy of the coelacanth muscles has been examined very thoroughly, their protein composition has, until recently, not been investigated. Thanks, however, to the 1972 British–French–American expedition to the Comores, frozen material has been made available and some results on myoglobin and four glycolytic enzymes have already been published. We have carried out a comparison of the sarcoplasmic proteins of red and white muscle by starch-gel electrophoresis. The ninhydrin-positive dialysable constituents and the myofibrillar proteins of white muscle have also been examined.A few puzzling results obtained with the white muscle extracts have been related to the occurrence of o.1 M ammonia, due presumably to the splitting of urea by a bacterial urease, and to an alteration of the active thiol groups of GAPDH and PK. If due account is taken of these unusual post-mortem changes, the extractability of the proteins and their properties are strikingly similar to those of teleosteans. The comparison of the sarcoplasmic proteins of white and red muscle by starch-gel electrophoresis revealed also that the differentiation observed in the coelacanth was similar to that occurring in the carp. A study of the low-molecular-weight proteins, or parvalbumins, of white muscle and of the myofibrillar proteins also shows the expected differences between the two muscle types.The only abnormal features observed in this study were the high concentration of parvalbumins, 1.5–2 times that found in other species examined, and the occurrence of an unusual globulin fraction which was easily extracted at ionic strength 0.5 and insoluble at ionic strength 0.35 and neutral pH.
TL;DR: A slow-moving hemoglobin with electrophoretic mobility similar to that of hemoglobin S was discovered in a white laboratory technologist who had an elevated reticulocyte count, as did several members of her family and her red cell survival was shortened.
Abstract: A slow-moving hemoglobin with electrophoretic mobility similar to that of hemoglobin S was discovered in a white laboratory technologist. She had an elevated reticulocyte count, as did several members of her family. Her red cell survival was shortened. Amino acid analysis indicated that leucine at position beta48 (CD7) had been replaced by arginine. The abnormal hemoglobin, called Okaloosa, was heat-precipitable and had decreased oxygen affinity. It exhibited a greater change in oxygen affinity than hemoglobin A when 2,3 DPG was added to "stripped" hemolysates. These findings cannot be readily explained by current views of structure-function relationships in the hemoglobin molecule. However, it is of interest that the amino acid in position CD7 is normally leucine in the alpha, beta, delta, and gamma-hemoglobin chains and in the myoglobin chain of man and a wide variety of other vertebrates.
TL;DR: Hemoglobin-oxygen equilibria in the presence of COHb resembles theEquilibria of more primitive forms of hemoglobin and gives rise to the suggestion that this decrease in the access to oxygen is a form of counterevolution.
Abstract: Carboxyhemoglobin (COHb) alters the oxyhemoglobin dissociation curve in such a manner that oxygen is released to the tissues with great difficulty and at a lower oxygen tension. The known effects on heart and brain of breathing .Sow concentrations of carbon monoxide are primarily related to this leftward shift and perhaps also to combination with myoglobin and certain iron-containing enzymes. Hemoglobin-oxygen equilibria in the presence of COHb resembles the equilibria of more primitive forms of hemoglobin and gives rise to the suggestion that this decrease in the access to oxygen is a form of counterevolution.
TL;DR: Chick embryos in ovo incorporated radioactivity from lysine-U- 14 C into myoglobin, as measured by an immunoprecipitation technique, and adult birds possessed equivalent amounts of myoglobin in heart and thigh muscle while pectoral muscle and liver tissue had no detectable myoglobin content.
TL;DR: The red muscles of Pila virens have a comparatively higher content of moisture, lipids, glycogen, iron, myoglobin and phosphorus, and their localization in regions of repetitive activity could be physiologically compared to vertebrate red muscles.
TL;DR: The quantum yield, [unk], is reported for the photodissociation of CO from reduced carboxymethylated cytochrome c, and is low relative to that for myoglobin and are pH-independent.
Abstract: The quantum yield, [unk], is reported for the photodissociation of CO from reduced carboxymethylated cytochrome c. The values of [unk] obtained are low relative to that for myoglobin and are pH-independent, being 0.23 at pH6.1 and 0.27 at pH9.7.
TL;DR: Kinetic studies of the reaction between carbon monoxide and (piperidine)2 Fe(porphyrin) complexes show that the mechanism involves predissociation to a five-co-ordinate (pipersidine)Fe(porPHyrin), and the data for the protoporphyrin IX system suggest that the model may resemble closely in kinetic properties the active iron site in deoxy-myoglobin and -hemoglobin.
Abstract: Kinetic studies of the reaction between carbon monoxide and (piperidine)2Fe(porphyrin) complexes to give (piperidine)Fe(CO)(porphyrin) show that the mechanism involves predissociation to a five-co-ordinate (piperidine)Fe(porphyrin) complex; the data for the protoporphyrin IX system suggest that the model may resemble closely in kinetic properties the active iron site in deoxy-myoglobin and -hemoglobin.