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Showing papers on "Myoglobin published in 1976"


Journal ArticleDOI
TL;DR: The detailed results show that the displacement of the iron atom from the plane of the porphyrin ring increases from 0·40 to 0·55 A on going from met to deoxy.

339 citations


Journal ArticleDOI
TL;DR: The results show that if the equilibrium binding curve for NO could be determined experimentally, it would show cooperativity with Hill's n at 50% saturation of about 1.6.

292 citations


Journal ArticleDOI
TL;DR: Work performance on a treadmill has been evaluated in normal and iron-deficient rats, and iron therapy corrected the disability within 4 days at a hemoglobin compatible with normal work performance.
Abstract: Work performance on a treadmill has been evaluated in normal and iron-deficient rats. Anemia was removed as a variable by adjusting the hemoglobin of all animals to the same concentration. At a hemoglobin compatible with normal work performance, iron-deficient animals showed a marked impairment of running ability as compared to control animals. Iron therapy corrected the disability within 4 days. Concentrations of the cytochrome pigments and myoglobin, and rates of oxidative phosphorylation with pyruvate-malate, succinate, and alpha-glycerophosphate as substrates were all reduced in mitochondrial preparations from skeletal muscle of iron-deficient rats, but only the rate of phosphorylation with alpha-glycerophosphate as substrate increased significantly and in parallel with the recovery in work performance of the iron-deficient rats treated with iron dextran.

287 citations


Journal ArticleDOI
TL;DR: Even though some of the protein--sodium dodecyl sulfate complexes have helical contents as high as 50%, their overall conformation more closely approximates that of a random coil than a rod.
Abstract: Circular dichroism spectra have been obtained for albumin, alpha-chymotrypsinogen, collagen, concanavalin A, elastase, hemoglobin, histone f2b, alpha-lactalbumin, lactate dehydrogenase, beta-lactoglobulin, lysozyme, myoglobin, papain, ribonuclease A, and thermolysin in the presence of sodium dodecyl sulfate and dithiothreitol. While all spectra have the shape anticipated for a mixture of random coil and alpha helix, the intensities differ markedly ([theta]222 ranges from --1400 to --15 000 deg cm2/dmol). The variation in the circular dichroism can be quantitatively explained by a model which assumes that the arginyl, histidyl, and lysyl residues have an enhanced probability of propagating a helical segment in the presence of the detergent. The model also permits the computation of dimensional properties (unperturbed end-to-end distance and radius of gyration) for polypeptides of known amino acid sequence. Such computations have been performed for 67 proteins. The computed dimensions are compatible with experimental values and with the molecular weight dependence of the transport properties of the complexes. Furthermore, the model can account for the abnormal transport properties of the sodium dodecyl sulfate complexes formed by ribonuclease A, collagen fragments, and histones f2a1, f2a2, f2b, and f3. Even though some of the protein--sodium dodecyl sulfate complexes have helical contents as high as 50%, their overall conformation more closely approximates that of a random coil than a rod.

231 citations


ComponentDOI
19 May 1976

171 citations



Journal ArticleDOI
TL;DR: The results as a whole show that the two methionine side chains undergo continuous variations in environment, and that these variations are controlled by events at a distance within the protein structure.

80 citations


Journal ArticleDOI
TL;DR: The interpretation of the infrared results suggests that the primary force altering vCO in these heme proteins is a variation in electron density at the heme iron and not direct protein interactions with the CO ligand.
Abstract: Infrared difference spectra, FeIIICO vs. FeIII of horseradish peroxidase isoenzymes A2 and C were recorded from 2000 to 1800 cm-1. Under alkaline conditions, pH 9, both isoenzymes exhibit two CO stretching bands, at 1938 and 1925 cm-1 for A2 and at 1933 and 1929 cm-1 for C. As the pH is lowered the low-frequency band for each isoenzyme decreases in intensity with a concommitant appearance and increase in intensity of a band at 1906 and 1905 cm-1 for the A2 and C isoenzymes, respectively. These changes conform to pK values of 6.7 for the A2 and 8.8 for the C isoenzymes of horseradish peroxidase. The interpretation of the infrared results was simplified by the observation that a linear relationship exists between the redox potential, Em7, for the FeIII/FeII system vs. the infrared CO stretching frequency, vCO, for cytochrome a3, hemoglobin, myoglobin, and cytochrome P-450 cam with substrate. This relationship suggests that the primary force altering vCO in these heme proteins is a variation in electron density at the heme iron and not direct protein interactions with the CO ligand. The horseradish peroxidase infrared bands in the 1930-cm-1 region correlate well with this relationship. The large deviation of the 1905-cm-1 band from the linear relationship and its dependence upon hydrogen ion concentration are consistent with horseradish peroxidase having a single CO binding site which can hold in two geometries, one of which contains an amino acid moiety capable of forming a hydrogen bond to the carbonyl oxygen.

73 citations


Journal ArticleDOI
TL;DR: The concomitant increase in both the combination and dissociation rate constants with increase in electronegativity of the iron atom suggests that these reactions have different rate determining steps, although such a reaction process is contradictory to the generally accepted concept that in a reversible reaction, both on and off reactions proceed through the same transition state.

47 citations


Journal ArticleDOI
TL;DR: Fe-enriched complexes of hemoglobin and myoglobin with CO and O2 were photodissociated at 4.2 degrees K, and the resulting spectra were compared with those of the deoxy forms, indicating a well-defined iron environment.

45 citations


Journal ArticleDOI
TL;DR: It was concluded that the distinct shift of the pKa value in the case of peroxidase was attributable to the presence of a hydrogen bond between the sixth ligand and the distal base.

Journal ArticleDOI
TL;DR: From a comparison of the high and low spin sepctra of the myoglobin derivatives it is concluded that oxymyoglobin contains between 10 and 20% of a ferrous high spin component below 100 degrees K.

Journal ArticleDOI
TL;DR: By use of a newly constructed CD instrument, infrared magnetic circular dichroism (MCD) spectra were observed for various myoglobin derivatives and reinforced the assignment that the infrared band is the charge transfer transition to the degenerate excited state.

Journal ArticleDOI
TL;DR: Based on the structural features investigated, the more open configuration of the tuna myoglobin and its smaller α-helical content were felt to be the most obvious causes of the relative instability of this protein compared to whale myoglobin.
Abstract: 1. 1. This paper presents information on the isolation, purification, and characterization of myoglobins from yellowfin tuna, Thunnus albacares . 2. 2. Data presented include amino acid composition, isoelectric point, reactivity of histidine and sulfhydryl residues, chromatographic behavior, optical rotatory dispersion, sedimentation coefficient, and mol. wt. 3. 3. The susceptibility of tuna myoglobin to denaturation by urea and heat has been compared to that of sperm whale myoglobin. 4. 4. Based on the structural features investigated, the more open configuration of the tuna myoglobin and its smaller α-helical content were felt to be the most obvious causes of the relative instability of this protein compared to whale myoglobin.

Journal ArticleDOI
TL;DR: The results are indicative that, during the course of denaturation, the conformational changes in the tryptophanyl segment are not thoroughly concomitant with those involving the heme pocket.

Journal ArticleDOI
TL;DR: Results indicate that affinities of ferric myoglobin for ligands, in contrast to those of the ferrous form for oxygen and carbon monoxide, are determined by the number of the formyl groups and that two vinyl groups at position 2 and 4 are equivalent in the binding of various ligands by ferricmyoglobin.

Journal ArticleDOI
TL;DR: The method of CD investigation of polymer-bound peptide sequences during the peptide synthesis in solution enables one to determine the influence of protecting groups and the chain end of a peptide on its conformation.
Abstract: The conformation of polyethylene glycol-bound peptides, synthesized by the liquid-phase method, was investigated. This marcromolecular C-terminal protecting group is transparent in the visible and the ultraviolet range to 190 nm and solubilizes peptides in many different solvents. The CD spectra of the polymer-bound myoglobin sequence 66–73 and of the biologically active undecapeptide “substance P” were measured in each step of the synthesis. In both examples the formation of a secondary structure during the growth of the peptide chain was found. In the hydrophobic octapeptide containing the myoglobin sequence 66–73, the influence of either the blocked or the free N-terminal amino group on the conformation was observed. The blocked octapeptide in trifluoroethanol showed a higher degree of α-helix contribution than in its free state. The conformation of the polyethylene glycol-bound nona- and decaalanine in trifluoroethanol and water was determined. The peptide with a free amino end group has β-conformation in trifluoroethanol as well as in water. The corresponding N-Boc-protected derivatives show helical structure. The amino end group has a decisive influence on the formation of β-structure. The method of CD investigation of polymer-bound peptide sequences during the peptide synthesis in solution enables one to determine the influence of protecting groups and the chain end of a peptide on its conformation. It is also possible to study the relationship between the secondary structure, the chain length, and the kinetic of the coupling reaction in different solvents. Since the crystallization method for the liquid-phase peptide synthesis allows one to synthesize peptides in very short time, a new method of studying peptide conformations is opened.

Journal ArticleDOI
TL;DR: Measurements of pH-dependence for ferric horseradish peroxidase and horse heart myoglobin covering the large hyperfine shift of heme ring methyl groups due to ferric high spin state confirmed the result of magnetic susceptibility measurements by Theorell and Ehrenberg, and was able to distinguish the nature of the pH dependent spin state change between both hemoproteins.

Journal ArticleDOI
TL;DR: Comparison with other ungulates shows that pig myoglobin is far from other artiodactyls previously studied and close to the eutherian ancestral chain.

Journal ArticleDOI
TL;DR: A method for the determination of haemoglobin in ovine muscle is described and pigments were separated on columns of Sephadex G75 or G50 and quantitated spectrophotometrically.

Journal ArticleDOI
TL;DR: When a cured meat model system was made from white muscle it contained less residual nitrite than if it were made from a red muscle; this effect is due to the lower pH of white muscle.
Abstract: When a cured meat model system was made from white muscle it contained less residual nitrite than if it were made from a red muscle; this effect is due to the lower pH of white muscle. If the pH of red and white muscle is similar then the slightly lower residual nitrite in products made from red muscle probably is due to the greater content of myoglobin in red muscle.

Journal ArticleDOI
TL;DR: In vitro activity of the anaerobic enzymes phosphofructokinase and lactic dehydrogenase from axial muscle tissue of Coluber constrictor, Crotalus viridis and Lichanura roseofusca was shown to correlate with levels of lactate production during activity by these snakes, and Coluber was showed to have the most complex lung structure and highest muscle myoglobin content.
Abstract: In vitro activity of the anaerobic enzymes phosphofructokinase and lactic dehydrogenase from axial muscle tissue of Coluber constrictor, Crotalus viridis and Lichanura roseofusca was shown to correlate with levels of lactate production during activity by these snakes Additionally, gross and histological lung structure and axial muscle myoglobin concentration were investigated in these species Coluber was shown to have the most complex lung structure and highest muscle myoglobin content These are interpreted to be correlated with high aerobic scope in Coluber Finally, the ophidian saccular lung is postulated to assist in maintenance of high tidal volume

Journal ArticleDOI
TL;DR: In this paper, routees are developed for synthesis of porphyrins carrying functionalised bridges over the macrocycle; the FeII complexes of these products are of interest in relation to myoglobin and haemoglobin.
Abstract: Routes are developed for synthesis of porphyrins carrying functionalised bridges over the macrocycle; the FeII complexes of these products are of interest in relation to myoglobin and haemoglobin.

Journal ArticleDOI
TL;DR: Using Resonance Raman spectroscopy (RRS), direct experimental evidence is presented to support the existence of two distinct forms of MbOH and the predominant form is identified as the high spin pH=l 1.6.

Journal ArticleDOI
TL;DR: Cytochrome P-450 was solubilized from phenobarbital induced rabbit liver and purified by affinity chromatography and produced small but significant increases in NMR rates both in the H2O and in the 2H2O solution, while binding of aniline doubled the rates.

Journal ArticleDOI
TL;DR: The amino acid sequence of rabbit myoglobin was determined and it contains 153 amino acid residues and differs in three of them from all known mammalian myoglobins: Ala 5, His 34 and Thr 35.

Journal ArticleDOI
TL;DR: Both coelomic cell hemoglobin and body wall myoglobin appear to be homogeneous pigments under the conditions described and the amino acid compositions of the two pigments are reported.
Abstract: 1. 1. The polychaete annelid Glycera robusta contains both a coelomic cell hemoglobin and a body wall myoglobin. 2. 2. The coelomic cell hemoglobin in the oxy-, carbonmonoxy- and cyanmet-forms has an apparent molecular weight on Sephadex G-100 of about 48.000–50.000 and an S 20,w value of 3·9. Some evidence of an association-dissociation equilibrium is present. This pigment is composed of 14,000–16,000 mol wt subunits as determined by SDS gel electrophoresis and chromatography on Sephadex G-200 of the carboxymethylated globin in 8 M urea. 0·1 M in 2-mercaptoethanol. The hemoglobin contains 1 g atom iron per 17,500 g hemoglobin. 3. 3. The body wall myoglobin is monomeric with a mol. wt of 17,000 on Sephadex G-100 and 15,000 on SDS gel electrophoresis. This pigment contains 1 g atom iron per 16,000 g hemoglobin. 4. 4. Both coelomic cell hemoglobin and body wall myoglobin appear to be homogeneous pigments under the conditions described. 5. 5. The amino acid compositions of the two pigments are reported. 6. 6. The structures of these pigments are compared with those of other annelid hemoglobins.

Journal ArticleDOI
TL;DR: C2H5N13C appears as a more sensitive probe than 13CO for hemoprotein NMR studies because of its characteristic resonances assigned to α, β and γ subunits.

Journal ArticleDOI
TL;DR: The reactions of this hemoglobin with both ligands were found to be more rapid than the corresponding reactions involving myoglobin and were also biphasic in nature, the rate constants being approximately an order of magnitude different for the fast and slow phases in each case.

Journal ArticleDOI
TL;DR: The primary structure of the myoglobin of the domestic dog (German shepherd) was studied and shows 16 differences versus badger, 20 versus harbour seal and 15 versus California sea lion.