Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q0Z944 (hemoglobin)
 63,986 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Occasional complications and even death in subjects with sickle cell trait have been attributed to severe physical exertion. However, the extent to which sickling actually occurs during exercise has not been reported. This study examined the red blood cell morphological features immediately following near maximal upright graded bicycle exercise in five asymptomatic black subjects with hemoglobin AS. Exercise produced minimal sickling in vivo, which was not proportional to the intensity of exercise. The amount of sickling in vivo was small in comparison to that observed in the presence of severe hypoxia in vitro, never exceeding 0.75%. in seven normal subjects with hemoglobin AA, exercise did not cause changes in red blood cell morphological features. We conclude that exercise may initiate sickling in subjects with sickle cell trait.
Arch Intern Med 1976 Sep
PMID:Morphological features of red blood cells in subjects with sickle cell trait: changes during exercise. 0 40

An extracellular protease has been purified from cultures of Pseudomonas fluorescens. It is a metalloenzyme with a molecular weight of 37,000 +/- 3,700, able to digest casein, hemoglobin and gelatine.
Experientia 1976 Sep 15
PMID:The extracellular protease from Pseudomonas fluorescens. 0 11

The pH dependence of the apparent tetramer to dimer dissociation constant has been determined at 20 degrees for both oxy- and deoxyhemoglobins A and Kansas. These measurements were made by three different procedures: gel chromatography, sedimentation velocity, and kinetic methods in either of three buffer systems: 0.05 M cacodylate, Tris, or glycine with 1 mM EDTA and 0.1 M NaCl between pH 6.5 and 11. The tetramer-dimer dissociation constant of human oxyhemoglobin A decreases from about 3.2 X 10(-6) M at pH 6.0 to about 3.2 X 10(-8) M at pH 8.5. The slope of this line indicates that the dissociation of tetramer to dimer is accompanied by the uptake of about 0.6 protons per mol of tetramer in this region. The corresponding dissociation constant for deoxyhemoglobin in the same pH region increases apparently almost linearly from 1.0 x 10(-12) M at pH 6.5 to about 1.0 x 10(-5) M at pH 11. To dimer is associated with the release of about 1.6 protons per mol of tetramer. Comparison of these data with the known proton release accompanying the oxygenation of tetramers confirms that the pH dependence of oxygen binding by dimers must be very small. The present data predict that the overall proton release or uptake per oxygen bound by dimer should be less than 0.1. The tetramer-dimer dissociation equilibria of oxy- and deoxyhemoglobins above pH 8.5 have identical pH dependences. In this range the dissociation constant of deoxy-Hb is about one-tenth that of oxyhemoglobin. Human oxyhemoglobin Kansas is known to have an enhanced tetramer-dimer dissociation compared with that of hemoglobin A. Below pH 8.5 the tetramer-dimer dissociation constant of Hb Kansas is about 400 times greater than that of HbA in the absence of phosphate buffers. In contrast, the tetramer-dimer dissociation constants of deoxyhemoglobins A and Kansas appear to be identical. These findings are consistent with previous structural observations on these hemoglobins. The data on the tetramer-dimer dissociation of human hemoglobin were used to calculate the total free energy of binding of oxygen to the tetramer and the median oxygen pressure on the basis of fundamental linkage relations and a pH-independent estimate of the total free energy of binding oxygen to dimer. Simulated oxygen binding curves were generated with the equations of Ackers and Halvorson (Ackers, G. K., and Halvorson, H. (1974) Proc. Natl. Acad. Sci. U.S.A. 71, 4312-4316) by making two assumptions: (a) that the dimers are noncooperative and pH-independent in O2 binding and (b) that the distribution of cooperative energy in the oxygenation of tetramers is independent of pH. We have compared these simulations with experimental data obtained at low protein concentrations (30 to 124 muM heme) to show that the variation in oxygen affinity with pH can be described in terms of the subunit equilibria. We conclude that an accurate analysis of the contributions of individual oxygen binding steps to the Bohr effect cannot be made without considering the contributions of the dimers to oxygen binding...
J Biol Chem 1976 Sep 25
PMID:Tetramer-dimer dissociation in homoglobin and the Bohr effect. 0 90

The inhibitory effect of dioctyl sodium sulfosuccinate on hog pepsin activity was investigated over the pH 1.5-3.0 range. The inhibitory effect was studied using a natural substrate, hemoglobin, and a synthetic substrate, N-acetyl-L-diiodotyrosine. The mechanistic studies revealed that a substrate-inhibitor interaction was the major mechanism of inhibition with hemoglobin. However, some direct enzyme inhibition also was involved. With the synthetic substrate, the inhibition las due to a competition between the substrate and the inhibitor molecules for the enzyme. The possible therapeutic significance of the inhibitory effect of the medicinal surfactant is discussed.
J Pharm Sci 1976 Sep
PMID:Dc Polarographic assay of tetracyclines. 0 3

The kinetic inhibition of the gelation of hemoglobin S is compared to the change in hemoglobin S soulbility, when the solubility is altered by carbon monoxide, pH, or urea. By means of a new technique, the delay time and the extent of gelation are measured on the same sample. They delay time, td, is found to be proportional to a high power (30-40) of the hemoglobin S solubility. Togehter with the previously reported concentration dependence, this result demonstrates that the rate is proportional to a high power of the supersaturation, S, defined as the ratio of the total hemoglobin S concentration to the equilibrium solubility. The results obey the supersaturation equation td-1 = gammaSn, where gamma is an empirical constant (about 10(-7) sec-1) and n is about 35. The supersaturation equation can successfully account for observations on the kinetics of cell sickling and is therefore used to estimate the increase in the delay time for sickling necessary to produce significant clinical benefit to patients with sickle cell disease.
Proc Natl Acad Sci U S A 1976 Sep
PMID:Supersaturation in sickle cell hemoglobin solutions. 0 40

Up until now it has been assumed that the protease-binding property of alpha1-protease inhibitor (alpha1PI) was destroyed by acid starch gel electrophoresis (pH 4.9). Analyses on acid starch gel blocks for pH and conductivity changes during and following a typical electrophoretic run showed that it was unlikely that the separating alpha1PI would be exposed to pH values lower than 6.2, and that the allele products, following the passage of the buffer front, were in an environment of constant pH(6.3), extremely low conductivity and high field strength. These results strongly suggested the likelihood that alpha1-PI would be chemically and physically unchanged as a result of exposure to acid starch gel electrophoresis. In order to test this likelihood, human serum was electrophoretically separated in acid starch gel and following electrophoresis, was immersed in 0.1 M diethylbarbiturate buffer, pH 8.6, containing 20 mug/ml of pancreatic elastase. The pH-adjusted (8.15) and elastase-impregnated starch gel layer was superimposed on hemoglobin-agar for 2.5 h at 37 degrees C followed by immersion of the hemoglobin-agar layer in 1% NaCl overnight, distilled water for 2 h, drying under filter paper and staining. The results showed zones of undigested hemoglobin indicating, unequivocally, that the separated alpha1PI allele products are capable of forming complexes with proteases and that alpha1PI is not inactivated following exposure to acid starch gel electrophoresis. Densitometric analysis of the transparent stained zones on a clear agar gel background offers an alternative to analysis of the acid starch gel-separated zones by antigen-antibody crossed electrophoresis and as such is suitable for identification of alpha1-protease inhibitor phenotypes. Further, the method is specific for alpha1PI and a densitometric scan provides direct information relative to the protease-binding capacity of the sample as well as the contribution of each alpha1PI allele product to that capacity.
Biochim Biophys Acta 1976 Sep 28
PMID:A new method for the determination of alpha1-protease inhibitor (alpha1-antitrypsin) phenotypes based on the formation of alpha1-protease inhibitor allele product-elastase complexes. 1

Red cell concentrations of hemoglobin (MCHC), H+, Na+, K+, Mg++, cl- were measured in femoral venous blood of six untrained (UT), six endurance trained (TR) and three semitrained (ST) subjects during graded increasing work (4, 8, 12, 18 and 24 mkp/s, 10-15 min on each step) on a bicycle ergometer. Before exercise no significant differences were detected for the measured variables when comparing UT and TR. During exercise MCHC, [Na+], [K+] and [Mg++] remained constant indicating lack of water shift into the erythrocytes in spite of a marked acidosis (lowest pH Blood value 7.225). This lack resulted from an elevated extracellular osmolality. [H+]Ery and [Cl-]Ery maximally increased by 2.0 X 10(-8) eq/kg H2O and 10 meq/l, respectively. The change was markedly greater in UT than in TR at equal load. However, if [H+] Ery and [Cl-] Ery were related to pH of whole blood, differences between groups, almost disappeared and the ions were distributed as predictable from in vitro experiments (Fitzsimmons and Sendroy, 1961). Behaviour of H+ and Cl- may be of importance for oxygen dissociation under in vivo conditions.
Eur J Appl Physiol Occup Physiol 1976 Sep 23
PMID:Red cell hemoglobin, hydrogen ion and electrolyte concentrations during exercise in trained and untrained subjects. 1 Jan 57

Using NO and CO as ligands the Bohr effect of human hemoglobin has been measured with and without inositolhexophosphate. It appears that in the absence and presence of inositolhexaphosphate hemoglobin shows a distinct ligand specificity with respect to the Bohr effect. Ligation with NO is accompanied by release of a larger number of Bohr effect. It is shown that this latter result is due to the fact that the number of protons taken up upon binding of inositolhexaphosphate to ligated hemoglobin is larger for HbNO than for HbCO. It is suggested that this additional proton uptake is partially due to a restoration of the saltbridge between His 146beta and Asp 94beta upon addition of IHP.
Biophys Chem 1977 Sep
PMID:The CO and NO Bohr effect of human hemoglobin with and without inositolhexaphosphate. 2 Jan 74

Temperature-dependent change in hemoglobin-oxygen affinity was measured as a function of hemoglobin-oxygen saturation. In addition, the CO2 Bohr factor and fixed acid Bohr factor were measured as a function of saturation of temperatures of 23, 30, 37, and 44 degrees C. Measurements were made on normal blood and blood with reduced 2,3-diphosphoglycerate (DPG). The influence of temperature is greatest at low saturation and is enhanced slightly by DPG depletion. The CO2 Bohr factor is increased at high temperatures; this is primarily due to increased carbamino formation with rising temperature, especially at lower oxygen saturation. The effect of DPG on oxygen affinity is reduced at a high temperature and elevated at low temperature. These diverse effects of temperature on hemoglobin-ligand interaction require consideration in assessing oxygen delivery when temperature is increased or decreased.
J Appl Physiol Respir Environ Exerc Physiol 1977 Sep
PMID:Influence of temperature on hemoglobin-ligand interaction in whole blood. 2 Nov 54

To assess the adaptive value of the right-shift of the oxyhemoglobin dissociation curve (decreased affinity for oxygen) observed in humans upon altitude exposure, the short-term physiologic responses to altitude-induced hypoxia were evaluated in two subjects with a high oxygen affinity hemoglobin (Hb Andrew-Minneapolis) and in two of their normal siblings. In striking contrast to normal subjects, at moderately high altitude (3,100 m) the high affinity subjects manifested: (a) lesser increments in resting heart rate; (b) minimal increases in plasma and urinary erythropoietin; (c) no decrement in maximal oxygen consumption; and (d) no thrombocytopenia. There was no difference between subject pairs in 2,3-diphosphoglycerate response to altitude exposure. These results tend to contradict the belief that a decrease in hemoglobin oxygen affinity is of adaptive value to humans at moderate altitudes. Rather, they support the hypothesis that, despite disadvantages at low altitude, a left-shifted oxyhemoglobin dissociation curve may confer a degree of preadaptation to altitude.
J Clin Invest 1978 Sep
PMID:Human llamas: adaptation to altitude in subjects with high hemoglobin oxygen affinity. 2 54


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