Showing papers on "Myoglobin published in 1992"
TL;DR: The results indicate that the reaction of mAbs, whose specificity is precisely known and predetermined by the immunizing free peptide, can be markedly affected by substitutions outside the indicated binding region on the protein.
Abstract: Monoclonal antibodies (mAbs) of predetermined specificity were prepared by immunizing with a free (i.e., not conjugated to any carrier) synthetic peptide representing region 15–22 (site 1) of sperm whale myoglobin (SpMb). The cross-reactions of Mb variants with three mAbs were studied in order to determine whether such interactions are influenced by substitutions outsde the site. Finback whale Mb, which has no substitutions within region 15–22, showed lower cross-reactivity and relative binding affinity than the reference antigen, SpMb. Bottle-nose Atlantic dolphin myoglobin (BdMb) and badger myoglobin (BgMb), although they have identical substitutions within region 15–22 (Ala-15 to Gly and Val-21 to Leu), showed very different binding properties. The cross-reaction of BdMb was quite comparable to that of SpMb, while that of BgMb was much lower. Since the two proteins have identical structures in regions 15–22, the differences in their cross-reactivities are readily attributed to the effects of substitutions outside this region. Another pair of myoglobins, horse myoglobins (HsMb) and chicken myoglobin (ChMb), also have two identical substitutions (Ala-15 to Gly and Val-21 to Ile) within region 15–22, but possessed different cross-reactivity. The results indicate that the reaction of mAbs, whose specificity is precisely known and predetermined by the immunizing free peptide, can be markedly affected by substitutions outside the indicated binding region on the protein.
262 citations
TL;DR: The theoretical results confirm that a complete description of picosecond ligand recombination must include the dynamics of ligand movement in the distal portion of the heme pocket, and suggest that photo- and thermally dissociated ligand molecules experience similar kinetic and equilibrium barriers to rebinding.
140 citations
TL;DR: Recombinant human myoglobin mutants with the distal His residue replaced by Leu, Val, or Gln residues were prepared by site-directed mutagenesis and expression in Escherichia coli to study the ligand binding properties.
134 citations
TL;DR: Immunoturbidimetric myoglobin measurements could be useful in the early evaluation of patients with suspected myocardial infarction because this assay takes less than two minutes and gave myoglobin determinations of high analytical quality.
Abstract: Objective —To evaluate a rapid immunoturbidimetric assay for myoglobin and to investigate its clinical usefulness in the early detection of acute myocardial infarction. Design —Prospective study. Immunoturbidimetrically determined myoglobin concentrations were compared with radioimmunoassay results obtained with the same blood samples. The diagnostic performance of myoglobin determination was compared with creatine kinase and creatine kinase MB activity (current standard of routine diagnosis). Settings —Part 1: coronary care unit. Part 2: emergency room in a university hospital. Patients —Part 1: 30 patients with acute myocardial infarction admitted not later than four hours (median two hours) after the onset of symptoms. Part 2: 126 patients admitted to the emergency room with chest pain not caused by trauma (51 cases of acute myocardial infarction, 51 cases of angina pectoris, and 24 cases of chest pain not related to coronary artery disease). Interventions —Part 1: routine treatment including intravenous thrombolytic treatment (28 patients). Part 2: routine emergency treatment without thrombolytic treatment. Main outcome measures —The analytical quality of the immunoturbidimetric myoglobin assay and a comparison between the myoglobin assay and creatine kinase and creatine kinase MB for diagnostic sensitivity and performance. Results —The immunoturbidimetric myoglobin assay was fast and convenient and gave myoglobin determinations of high analytical quality. The concentration of myoglobin increased, peaked, and returned to the reference range significantly earlier than creatine kinase (p≤ 0·0001) and creatine kinase MB (p≤ 0·0002). Before thrombolytic therapy was started the diagnostic sensitivity of myoglobin was significantly higher than that of creatine kinase MB activity 0–6 h after the onset of chest pain and significantly higher (0·82 ν 0·29) than creatine kinase 2–4 h after the onset of chest pain. In almost all patients (92%) plasma myoglobin concentrations were increased 4–6 h after the onset of chest pain. Conclusion —Myoglobin was more sensitive in detecting early myocardial infarction than creatine kinase and creatine kinase MB activity. Immunoturbidimetric myoglobin measurements could be useful in the early evaluation of patients with suspected myocardial infarction because this assay takes less than two minutes.
133 citations
TL;DR: The CD spectrum changes upon adsorption were significant in the “soft” protein molecules (myoglobin, hemoglobin, and BSA), while they were insingnificant in the“rigid” proteins (RNase A and peroxidase).
Abstract: The conformational changes in well-characterized model proteins [bovine ribonuclease A (RNase A), horseradish peroxidase, sperm-whole myoglobin, human hemoglobin, and bovine serum albumin (BSA)] upon adsorption on ultrafine polystyrene (PS) particles have been studied using circular dichroism (CD) spectroscopy. These proteins were chosen with special attention to molecular flexibility. The ultrafine PS particles were negatively charged and have average diameters of 20 or 30 nm. Utilization of these ultrafine PS particles makes it possible to apply the CD technique to determine the secondary structure of proteins adsorbed on the PS surface. Effects of protein properties and adsorption conditions on the extent of the changes in the secondary structure of protein molecules upon adsorption on ultrafine PS particles were studied. The CD spectrum changes upon adsorption were significant in the "soft" protein molecules (myoglobin, hemoglobin, and BSA), while they were insignificant in the "rigid" proteins (RNase A and peroxidase). The soft proteins sustained a marked decrease in alpha-helix content upon adsorption. Moreover, the native alpha-helix content, which is given as the percentage of the alpha-helix content in the free proteins, of adsorbed BSA was found to decrease with decreasing pH and increase with increasing adsorbed amount. These observations confirm some well-known hypotheses for the confirmational charges in protein molecules upon adsorption.
127 citations
120 citations
TL;DR: This cyanobacterial myoglobin, referred to as cyanoglobin, was shown to be a soluble hemoprotein of 12.5 kilodaltons with an amino acid sequence that is related to that of myoglobins from two lower eukaryotes, the ciliated protozoa Paramecium caudatum and Tetrahymena pyriformis.
Abstract: Myoglobin was found in the nitrogen-fixing cyanobacterium Nostoc commune. This cyanobacterial myoglobin, referred to as cyanoglobin, was shown to be a soluble hemoprotein of 12.5 kilodaltons with an amino acid sequence that is related to that of myoglobins from two lower eukaryotes, the ciliated protozoa Paramecium caudatum and Tetrahymena pyriformis. Cyanoglobin is encoded by the glbN gene, which is positioned between nifU and nifH-two genes essential for nitrogen fixation-in the genome of Nostoc. Cyanoglobin was detected in Nostoc cells only when they were starved for nitrogen and incubated microaerobically.
113 citations
TL;DR: Evidence is provided for an injury of slow-twitch skeletal muscle fibers in response to eccentric contractions through measurements of torque production and magnetic resonance imaging of the involved muscle groups.
Abstract: The effects of a single series of high-force eccentric contractions involving the quadriceps muscle group (single leg) on plasma concentrations of muscle proteins were examined as a function of time, in the context of measurements of torque production and magnetic resonance imaging (MRI) of the involved muscle groups. Plasma concentrations of slow-twitch skeletal (cardiac beta-type) myosin heavy chain (MHC) fragments, myoglobin, creatine kinase (CK), and cardiac troponin T were measured in blood samples of six healthy male volunteers before and 2 h after 70 eccentric contractions of the quadriceps femoris muscle. Screenings were conducted 1, 2, 3, 6, 9, and 13 days later. To visualize muscle injury, MRI of the loaded and unloaded thighs was performed 3, 6, and 9 days after the eccentric exercise bout. Force generation of the knee extensors was monitored on a dynamometer (Cybex II+) parallel to blood sampling. Exercise resulted in a biphasic myoglobin release profile, delayed CK and MHC peaks. Increased MHC fragment concentrations of slow skeletal muscle myosin occurred in late samples of all participants, which indicated a degradation of slow skeletal muscle myosin. Because cardiac troponin T was within the normal range in all samples, which excluded a protein release from the heart (cardiac beta-type MHC), this finding provides evidence for an injury of slow-twitch skeletal muscle fibers in response to eccentric contractions. Muscle action revealed delayed reversible increases in MRI signal intensities on T2-weighted images of the loaded vastus intermedius and deep parts of the vastus lateralis. We attributed MRI signal changes due to edema in part to slow skeletal muscle fiber injury.(ABSTRACT TRUNCATED AT 250 WORDS)
112 citations
TL;DR: The present studies show that the peroxide-generated myoglobin radical readily exchanges between remote loci, including non-tyrosine residues, but protein cross-linking only occurs when radical density is located on Tyr-151, and that protein dimers are only formed when Tyr- 151 is present.
111 citations
TL;DR: The reactivity of several thiols, including glutathione, dihydrolipoic acid, cysteine, N-acetyl cy Steine, and ergothioneine, as well as several disulfides, toward different redox states of myoglobin, mainly met-myoglobin and ferrylmyoglobin, was evaluated by optical spectral analysis, product formation, and thiyl free radical generation.
107 citations
TL;DR: The collision-induced dissociation spectra of the [M + H]+ ions of the tryptic peptides from the horse myoglobins and the chymotriptic peptide from sperm whale myoglobin proved that in both proteins amino acid 122 is indeed aspartic acid, rather than asparagine.
Abstract: Myoglobins from horse heart muscle, horse skeletal muscle and sperm whale are widely used as calibration standards or test compounds for various mass spectrometric methodologies. In all such cases reported in the literature, a molecular weight value is used (16,950.5 and 17,199, respectively) which is based on the assumption that amino acid 122 in this 153 amino-acid-long protein is asparagine, overlooking a published suggestion that it is aspartic acid instead. Since the mass assignment accuracy for matrix-assisted laser desorption mass spectrometry is reported to be +/- 0.01% and for electrospray ionization +/- 0.0025%, and error of one mass unit in approximately 17,000 would be significant. The mass-to-charge ratio of ions of the tryptic peptide encompassing amino acid 122 derived from commercially available horse heart and horse skeletal myoglobins, the apomyoglobin of the latter, and the tryptic and chymotryptic peptide of sperm whale myoglobin proved that in both proteins amino acid 122 is indeed aspartic acid, rather than asparagine. This finding was further confirmed by the collision-induced dissociation spectra of the [M + H]+ ions of the tryptic peptides from the horse myoglobins and the chymotriptic peptide from sperm whale myoglobin. Thus, the correct molecular weight of horse myoglobin is 16,951.49 and that of the sperm whale protein is 17,199.91.
TL;DR: Using suitable surface-modified electrodes, an electrochemical system which allows a reversible heterogeneous electron transfer at high protein concentrations between the electrode and myoglobin or hemoglobin in an optically transparent thin-layer electrochemical (OTTLE) cell is developed.
Abstract: Using suitable surface-modified electrodes, we have developed an electrochemical system which allows a reversible heterogeneous electron transfer at high (approximately 5 mM) protein concentrations between the electrode and myoglobin or hemoglobin in an optically transparent thin-layer electrochemical (OTTLE) cell. With this cell, which is transparent from 190 to 10,000 nm, we have been able to obtain electrochemically-induced Fourier-transform infrared (FTIR) difference spectra of both proteins. Clean protein difference spectra between the redox states were obtained because of the absence of redox mediators in the protein solution. The reduced-minus-oxidized difference spectra are characteristic for each protein and arise from redox-sensitive heme modes as well as from polypeptide backbone and amino acid side chain conformational changes concomitant with the redox transition. The amplitudes of the difference bands, however, are small as compared to the total amide I absorbance, and correspond to approximately 1% (4%) of the reduced-minus-oxidized difference absorbance in the Soret region of myoglobin (hemoglobin) and to less than 0.1% of the total amide I absorbance. Some of the bands in the 1560-1490-cm-1 spectral regions could be assigned to side-chain vibrational modes of aromatic amino acids. In the conformationally sensitive spectral region between 1680 and 1630 cm-1, bands could be attributed to peptide C = O modes because of their small (2-5 cm-1) shift in 2H2O. A similar assignment could be achieved for amide II modes because of their strong shift in 2H2O.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: The NOE and titration data were proposed to reflect the fact that several holoprotein structural elements, in particular outside the heme binding site, are maintained in the apoprotein.
Abstract: Proton NMR spectroscopy was applied to myoglobin in the ferric, water-liganded form (metMbH2O) and the apo form (apoMb) to probe the structure and stability of the latter. Proteins from sperm whale and horse skeletal muscles were studied to simplify the spectral assignment task. Nuclear Overhauser effects and the response of chemical shifts to variations of pH were used as indicators of residual native holoprotein structure in the apoprotein. The investigation was focused in the histidine side chains and their environment. In metMbH2O, the resonances of all imidazole rings not interacting with the heme were assigned by applying standard two-dimensional methods. These assignments were found to differ from those reported elsewhere [Carver, J. A., & Bradbury, J. H. (1984) Biochemistry 23, 4890-4905] except for His-12, -113, and -116. Only one histidine (His-36) has a pK(a) higher than 7, two (His-48 and His-113) have a pK(a) lower than 5.5, and two (His-24 and His-82) appear not to titrate between pH 5.5 and pH 10. In the apoproteins, the signals of His-113 and His-116, as well as those of His-24, -36, -48, and -119 previously assigned in the horse globin [Cocco, M. J.. & Lecomte, J. T. J. (1990) Biochemistry 29, 11067-11072], could be followed between pH 5 and pH 10. A comparison to the holoprotein data indicated that heme removal has limited effect on the pK(a) and the surroundings of these residues. Five additional histidines which occur in the two helices and connecting loops forming the heme binding site were identified in the horse apoprotein. Four of these were found to have pK(a) values lower than that expected of an exposed residue. The NOE and titration data were proposed to reflect the fact that several holoprotein structural elements, in particular outside the heme binding site, are maintained in the apoprotein. In the heme binding region of the apoprotein structure, the low pK(a)'s suggest local environments which are resistant to protonation.
TL;DR: Intracellular oxygen level can be determined in vivo with the signal intensity ratio of oxymyoglobin/deoxymyoglobin, reflected by the Val-E11 and His-F8 peaks in the 1H NMR spectra, and protein structure-function relationship in vivo can now be probed.
Abstract: The 1H NMR signal from oxymyoglobin, a low-concentration diamagnetic protein, is visible in myocardial tissue The methyl group of the Val-E11 resonates in a clear spectral region at -276 ppm and responds to dynamic changes in cellular oxygenation With CO, the signal shifts to -24 ppm The Val-E11 peak assignment and its response to oxygen and CO agree perfectly with previous myoglobin solution studies Intracellular oxygen level can now be determined in vivo with the signal intensity ratio of oxymyoglobin/deoxymyoglobin, reflected by the Val-E11 and His-F8 peaks in the 1H NMR spectra Moreover, protein structure-function relationship in vivo can now be probed
TL;DR: The mechanistic aspects of these results are discussed in terms of the two main redox transitions in the myoglobin molecule encompassing valence changes of the heme iron and electron transfer of the tyrosyl residue in the protein and linked to the two sequential one-electron oxidations of Trolox.
TL;DR: It is shown that the second oxidizing equivalent from the peroxide is rapidly transferred into the surrounding protein, generating a protein radical which has been detected by e.p.r. spectroscopy and demonstrated that this species is formed by electron transfer within the protein rather than by the generation and subsequent reaction of hydroxyl radicals (and related species from the other hydroperoxides).
Abstract: The root nodules of leguminous plants contain an oxygen-carrying protein which is somewhat similar to myoglobin. Reaction of the Fe3+ form of this protein (metleghaemoglobin; MetLb) with H2O2 is known to generate a ferryl [iron(IV)-oxo] species. This intermediate, which is analogous to Compound II of peroxidases and ferryl myoglobin, is one oxidizing equivalent above the initial level. In the present study it is shown that the second oxidizing equivalent from the peroxide is rapidly transferred into the surrounding protein, generating a protein radical which has been detected by e.p.r. spectroscopy; this reaction is analogous to that observed with metmyoglobin. An identical protein-derived species is observed with all three forms of MetLb tested (a, c1, c3) and with a number of other hydroperoxides and two-electron oxidants. This latter result, the observation that the concentration of this species is not affected by certain hydroxyl-radical scavengers, and the loss of the radical when the oxy or deoxy forms are used, demonstrate that this species is formed by electron transfer within the protein rather than by the generation and subsequent reaction of hydroxyl radicals (and related species from the other hydroperoxides). The e.p.r. signal of this species, which decays rapidly with a half-life of approx. 40 s, is consistent with the formation of a sterically constrained tyrosine-derived phenoxyl radical; protein-iodination experiments lend support to this assignment. Reaction between the radical and a number of other compounds has been observed, demonstrating that it is at least partially exposed on the surface of the protein. Analysis of the protein structure suggest that the radical may be centred on a tyrosine residue present at position 132 in the protein; this residue is close to the haem prosthetic group, which would facilitate rapid electron transfer.
TL;DR: In this paper, the authors performed mutational analysis of upstream sequences (nucleotide positions -373 to +7 relative to the transcriptional start site) linked to a firefly luciferase gene.
Abstract: To define transcriptional control elements responsible for muscle-specific expression of the human myoglobin gene, we performed mutational analysis of upstream sequences (nucleotide positions -373 to +7 relative to the transcriptional start site) linked to a firefly luciferase gene. Transient expression assays in avian and mammalian cells indicated that a CCCACCCCC (CCAC box) sequence (-223 to -204) is necessary for muscle-specific transcription directed either by the native myoglobin promoter or by a heterologous minimal promoter linked to the myoglobin upstream enhancer region. A putative MEF2-like site (-160 to -169) was likewise necessary for full transcriptional activity in myotubes. Mutations within either of two CANNTG (E-box) motifs (-176 to -148) had only minimal effects on promoter function. We identified and partially purified from nuclear extracts a 40-kDa protein (CBF40) that binds specifically to oligonucleotides containing the CCAC box sequence. A mutation of the CCAC box that disrupted promoter function in vivo also impaired binding of CBF40 in vitro. These data suggest that cooperative interactions between CBF40 and other factors including MEF-2 are required for expression of the human myoglobin gene in skeletal muscle.
Journal Article•
TL;DR: Findings suggests that among other factors, urine myoglobin may need to reach a critical level in order for myoglobinuric renal failure to ensue.
Abstract: Serum and urine myoglobin levels, measured by radioimmunoassay, were determined prospectively in eight patients with acute rhabdomyolysis, within 24 hours of admission. Five patients had urine myoglobin concentrations greater than 1,000 ng/ml (normal < 5 ng/ml); four of these patients subsequently developed acute renal failure. In three patients whose urinary myoglobin levels ranged from 19 to 275 ng/ml, acute renal failure did not occur. This difference in the occurrence of acute renal failure between the two patient groups was statistically significant (p < 0.05). Mean peak serum creatinine was significantly higher in the patients with high urine myoglobin (6.4 +/- 1.3 mg/dl) compared to those with low urine myoglobin (2.2 +/- 0.3 mg/dl), p < 0.02. There was no statistical correlation between level of serum creatine phosphokinase and serum or urine myoglobin, although the serum and urine myoglobin levels correlated well with each other. These findings suggests that among other factors, urine myoglobin may need to reach a critical level in order for myoglobinuric renal failure to ensue.
TL;DR: This process is examined with the help of 4-hydroperoxy-4-methyl-2-6-di-tert-butyl-cyclohexa-2,5-dien-1-one (BHTOOH), a compound that is converted heterolytically to an alcohol and homolytic to several rearranged products.
Abstract: Despite extensive work on homolytic versus heterolytic peroxide bond cleavage by iron porphyrins, the nature of the corresponding reactions catalyzed by myoglobin (Mb) and hemoglobin (Hb) remains unclear. These hemoproteins react with peroxides to give a ferryl (Fe IV =O) complex and a protein radical, but the coupling of dioxygen bond cleavage to protein radical formation is obscure. This process is examined here with the help of 4-hydroperoxy-4-methyl-2,6-di-tert-butyl-cyclohexa-2,5-dien-1-one (BHTOOH), a compound that is converted heterolytically to an alcohol and homolytically to several rearranged products
TL;DR: It is concluded that conversion of protein thiol residues to either thioselenides or mixed disulfides confers protection against irreversible peroxide-dependent oxidation and is suggested that Mixed disulfide formation by thiol transferase activity may help protectprotein thiols from irreversible oxidation by heme-activated hydroperoxides.
TL;DR: Myoglobin content is increased in species with high basal metabolic rate, high physical activity, prolonged diving capacity, fatigue resistance, and red muscle, whereas it is decreased in white muscle, iron-deficient animals, animals with sedentary lifestyles, and in animals and tissues with small fiber diameters such as avian or fish hearts.
Abstract: A novel, simple, rapid, sensitive and reproducible microassay is described for determination of myoglobin and hemoglobin content of myocardial and skeletal muscle biopsy specimens from various mammals, birds and fish. As little as 50 mg of tissue is needed and myoglobin concentrations lower than 1 mg% can be detected. Myoglobin and hemoglobin are separated at alkaline pH by ammonium sulfate extraction followed by ultrafiltration. Heme content is determined by absorption of the Soret band when the hemoprotein extract is visibly colored or more sensitively by its peroxidase activity when the extract has low color. The heme reacts with tertiary-butyl hydroperoxide and orthotolidine to generate a blue color. Hemoglobin content is correlated with myoglobin content and is related to aerobic capacity and blood flow to the tissue. Myoglobin content varied over 5 orders of magnitude up to 7 per cent of the weight of tissue, whereas hemoglobin content varied over 2 orders of magnitude up to 6 per cent of tissue weight. Myoglobin content is increased in species with high basal metabolic rate, high physical activity, prolonged diving capacity, fatigue resistance, and red muscle, whereas it is decreased in white muscle, iron-deficient animals, animals with sedentary lifestyles, and in animals and tissues with small fiber diameters such as avian or fish hearts.
TL;DR: Examination with the aid of a computer provides a full picture of the oxidation reaction of myoglobin as a function of oxygen pressures, and these results seem to be of primary importance from a point of view of clinical biochemistry of the oxygen supply, as well as of pathophysiology of ischemia, in red muscles such as cardiac and skeletal muscle tissues.
TL;DR: In this paper, a method was described for obtaining the axes of the diagonal paramagnetic susceptibility tensor for the low-spin cyanide complexes of distal point mutants of ferric sperm whale myoglobin (metMbCN) using the wild-type (WT) protein for that portion of the molecule unperturbed by the point mutation, together with the experimental dipolar shifts, to search for the Euler rotation that correctly converts the crystal coordinates to the magnetic axes.
Abstract: A method is described for obtaining the axes of the diagonal paramagnetic susceptibility tensor for the low-spin cyanide complexes of distal point mutants of ferric sperm whale myoglobin (metMbCN). It relies on using the crystal coordinates of the wild-type (WT) protein for that portion of the molecule unperturbed by the point mutation, together with the experimental dipolar shifts, to search for the Euler rotation that correctly converts the crystal coordinates to the magnetic axes
TL;DR: Findings provide new insight into the biomechanics of conformational changes in proteins and lend support to theoretical models invoking stored strain energy as the driving force for large amplitude correlated motions.
Abstract: Phase grating spectroscopy has been used to follow the optically triggered tertiary structural changes of carboxymyoglobin (MbCO) and carboxyhemoglobin (HbCO). Probe wavelength and temperature dependencies have shown that the grating signal arises from nonthermal density changes induced by the protein structural changes. The material displaced through the protein structural changes leads to the excitation of coherent acoustic modes of the surrounding water. The coupling of the structural changes to the fluid hydrodynamics demonstrates that a global change in the protein structure is occurring in less than 30 ps. The global relaxation is on the same time scale as the local changes in structure in the vicinity of the heme pocket. The observed dynamics for global relaxation and correspondence between the local and global structural changes provides evidence for the involvement of collective modes in the propagation of the initial tertiary conformational changes. The energetics can also be derived from the acoustic signal. For MbCO, the photodissociation process is endothermic by 21 +/- 2 kcal/mol, which corresponds closely to the expected Fe-CO bond enthalpy. In contrast, HbCO dissipates approximately 10 kcal/mol more energy relative to myoglobin during its initial tertiary structural relaxation. The difference in energetics indicates that significantly more energy is stored in the hemoglobin structure and is believed to be related to the quaternary structure of hemoglobin not present in the monomeric form of myoglobin. These findings provide new insight into the biomechanics of conformational changes in proteins and lend support to theoretical models invoking stored strain energy as the driving force for large amplitude correlated motions.
TL;DR: To elucidate the behavioural differences between beef muscles from the viewpoint of colour stability, oxymyoglobin was extracted at 2 h post mortem, purified from two different muscles (longissimus lumborum, stable and psoas major, unstable) and the autoxidation rate was measured.
TL;DR: Quantitative values for myoglobin oxygen fractional saturation were extracted from visible absorption spectra of myoglobin and hemoglobin solutions by analysis with three algorithms: classical least-squares, partial least-Squares, and stagewise multiple linear regression.
Abstract: Quantitative values for myoglobin oxygen fractional saturation were extracted from visible absorption spectra of myoglobin and hemoglobin solutions by analysis with three algorithms: classical least-squares, partial least-squares, and stagewise multiple linear regression. In an effort to mimic in vivo conditions, oxygen tensions and concentrations of myoglobin and hemoglobin solutions in separate cuvettes were varied independently. Transmission measurements were made through both cuvettes so that spectra contained contributions from both myoglobin and hemoglobin. Oxygen tensions in the myoglobin solutions spanned the rapidly varying region of the myoglobin oxygen saturation curve with pO2 ranging from 0 to 4.79 Torr, corresponding to fractional saturation values between 0 and 0.903. A range of hemoglobin oxygenations from fully oxygenated to fully deoxygenated was used. Estimation of myoglobin fractional saturation by the classical least-squares algorithm had a standard error (SEest) of 0.094, while the partial least-squares method resulted in an SEest of 0.070. Partial least-squares estimations resulted in an SEest of 0.041 when a limited wavelength range was used. The stagewise multiple linear regression method had an SEest of 0.052. Results indicate that stagewise regression and partial least-squares yielded estimates of myoglobin fractional saturation that were more accurate than those obtained from classical least-squares.
TL;DR: In the canine models of heart failure, myoglobin concentration was demonstrated to be correlated with biochemical and physiological indicators of myocardial performance, namely, mitochondrial and sarcoplasmic reticular ATPase activities, and cardiac output, systemic vascular resistance, pulmonary capillary wedge pressure and mean arterial pressure, respectively.
TL;DR: The data demonstrate that octa-alkylporphyrins can be productively used as models for protoporphyrin IX in studies of heme proteins with MCD spectroscopy.
TL;DR: It is proposed that the E10 Arg similarly hydrogen bonds to the bound O2 in Aplysia MbO2 and accounts for its strong ligand binding and slow dissociation rate.
TL;DR: The cDNA-derived amino acid sequence of Sulculus myoglobin showed no significant homology with any other globins, but, surprisingly, showed high homology (35% identity) with human indoleamine 2,3-dioxygenase, a tryptophan degrading enzyme containing heme.