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Query: UNIPROT:Q0Z944 (hemoglobin)
 63,986 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An experimental procedure was worked out in which rats were subjected to an exchange of erythrocytes, followed by acute anemia by means of hemodilution. One group of rats received erythrocytes with a high concentration of 2,3-diphosphoglycerate (DPG), and the other group was given erythrocytes with a low DPG concentration. The survival rate was equal in the two groups. Irrespective of DPG concentration, the rats whose hemoglobin concentration reached the lowest level died. The rats that died were also more acidotic than the others. The results indicate that the hemoglobin concentration and the pH value were more important determinants for survival than the DPG concentrations.
Scand J Clin Lab Invest 1975 Dec
PMID:Survival of rats subjected to acute anemia at different levels of erythrocyte 2,3-diphosphoglycerate. 0 46

Peptidases activities were compared in human leucocytes, guinea pig and human alveolar macrophages. Seversl endo- and exopeptides were characterized; some of them were active at acid pH and others at neutral and alkaline pH. Leucocytes and alveolar macrophages had proteolygic activity for hemoglobin, fibrinogen, collagen and elastin. Using synthetic substrates, several enzymes were characterized: arylamidase, aminopeptidase, carboxypeptidases A and B and cathepsins A and C. The enzymatic activities were much higher in alveolar macrophages than in leucocytes.
Clin Chim Acta 1976 Feb 02
PMID:[Studies on the activities of peptidases from human leucocytes, and human and guinea pig alveolar macrophages (author's transl)]. 0 98

The effects of varying pH and of increasing intracellular hemoglobin (Hb) concentration on red cell sickling and oxygen affinity were studied in whole blood from persons with sickle cell anemia (SS) and sickle cell trait (SA). Small increases in SS blood pH inhibited sickling, and small reductions in both SS and SA blood pH promoted sickling far more than accounted for by the Bohr effect. Sickling behavior correlated with minimum gelling concentrations (MGC) of deoxygenated hemolysates without 2,3-diphosphoglycerate. MGC values fell sharply when pH was lowered from 7.25 to 7.15 for HbS and from 7.15 to 6.90 for SA hemolysates, suggesting effects on specific ionic interactions involved in Hb gelation. Possible clinical counterparts are acute metabolic acidosis and alkalosis (prior to change in red cell 2,3-diphosphoglycerate), where the Bohr effect and oxygen affinity-independent effects of pH alterations on sickling would be additive. Osmotic shrinkage of HbS-containing red cells produced a large fall in oxygen affinity and a marked increase in sickling independent of that fall. The oxygen affinity and sickling properties of SA cells whose MCHC was raised to 40 per cent resembled those of unaltered SS cells, supporting a relationship between molecular aggregation of Hb and low oxygen affinity. Sickling of aerated SS cells in hypertonic saline depended upon partial Hb desaturation due to lowered oxygen affinity. Thus osmotic shrinkage of HbS-containing cells acts synergistically with partial deoxygenation to promote sickling. These conditions are present in the renal medulla, but may occur elsewhere in severe hyperosmolar states.
J Lab Clin Med 1976 Apr
PMID:Determinants of red cell sickling. Effects of varying pH and of increasing intracellular hemoglobin concentration by osmotic shrinkage. 0 63

An automated AutoAnalyzer method using 5:5'-dithiobis-2-nitrobenzoic acid is described for determining whole blood glutathione reductase (BGR) activity and for measuring in vitro activation of BGR with flavin adenine dinucleotide (FAD). BGR activity is expressed as mumoles glutathione regenerated from oxidized glutathione per ml of whole blood (WB) or per g of hemoglobin. The stimulatory effect of FAD on BGR activity divided by the activity without FAD determined the activity coefficient (AC). We found that NADPH and oxidized glutathione assay concentrations of 0.100 mmole/liter and 0.250 mmole/liter, respectively, in 0.1 mole/liter phosphate buffer, pH 7.4, gave consistent results when WB, before assay, was diluted 20-fold. WB samples to be stored are initially diluted 10-fold with distilled water and frozen. Prior to assay, two aliquots of the sample are diluted 2-fold, one aliquot with distilled water and another with 46 mumole/liter FAD. With sample and manifold dilutions the assay FAD concentrations is 1.0 mumole/liter: assay concentrations greater than 5.0 mumole FAD/liter were shown to be inhibitory. We examined blood samples from 617 children in the age range 6 to 60 months and determined the normal AC range to be between 1.00 and 1.35. Six weaned rats (23 days of age), maintained on a riboflavin-deficient diet, showed a mean AC of 1.23, 1.54, 2.02, and 2.41 at 23, 26, 30, and 36 days of age, respectively. Six control rats maintained an AC of 1.23 +/- 0.05 (SD) during the same period.
Am J Clin Nutr 1976 Jun
PMID:An automated flavin adenine dinucleotide-dependent glutathione reductase assay for assessing riboflavin nutriture. 0 81

An enzymatic rate assay is described for measuring cholesterol in serum. Cholesterol is analyzed by mixing 5 mul of sample with a reagent consisting of cholesterol esterase, cholesterol oxidase, catalase, acetylacetone, methanol, and hydroxypolyethoxydodecane in a ammonium phosphate buffer at pH 7.0. The rate of increase in absorbance of the dihydrolutidine product is measured at 37 degrees C and 405 nm. The change in absorbance between 4 and 10 min is used to calculate the cholesterol concentrations by using simultaneously determined free cholesterol standards. The change is linearly related to cholesterol concentration up to 4 g/liter. Samples containing bilirubin up to 200 mg/liter, uric acid up to 200 mg/liter, and hemoglobin up to 1 g/liter, or certain drugs (clofibrate, phenobarbital, nicotinic acid, salicylate, Ketochol, and Ovral) gave no interference. Ascorbic acid added to serum caused a positive interference. Lipemic samples gave values that were slightly lower than did the method of Abell et al., used for comparison. Our kinetic assay, compared with the method of Abell et al., the enzymatic assay used with Abbott's Bichromatic Analyzer, and the Technicon SMA 12/60 enzymatic procedure gave correlation coefficients of 0.992, 0.985, and 0.986, respectively.
Clin Chem 1976 Dec
PMID:Enzymatic rate method for measuring cholesterol in serum. 1 1

The primary metabolic defect in 5-oxoprolinuria is a generalized deficiency of glutathione synthetase. The activity of this enzyme was determined in cell-free extracts of erythrocytes from patients with 5-oxoprolinuria, their parents and a sibling as well as from normal control individuals. The following activities (pkat/mg of hemoglobin) for glutathione synthetase were obtained: homozygotes mean 0.10 (range 0.07-0.12), heterozygotes mean 3.1 (range 2.8-3.7) and control individuals mean 6.1 (range 5.4-6.7). These results indicate that 5-oxoprolinuria, i.e. the defective gluthione synthetase gene(s), is transmitted by autosomal recessive inheritance. Studies of the kinetics of the low remaining activity of erythrocyte glutathione synthetase in patients with 5-oxoprolinuria failed to reveal defective affinity for glycine, gamma-glutamyl-alpha-aminobutyrate, ATP and Mg2+ ions. Furthermore, the pH optimum, time curves and temperature dependence for the mutant enzyme activity did not significantly differ from the corresponding parameters observed with normal enzyme.
Clin Chim Acta 1976 Nov 15
PMID:Erythrocyte glutathione synthetase in 5-oxoprolinuria: kinetic studies of the mutant enzyme and detection of heterozygotes. 1 5

The Henderson-Hasselbalch equation has always occupied a central place in the description of the acid-base status of the blood. An equation of similar importance is the equation for the CO2 equilibration curve of blood in vitro. It is proposed to name this the Van Slyke equation: a - 24.4 = - (2.3 X b + 7.7) X (c - 7.40) + d/(1 - 0.023 X b), where a = bicarbonate concentration in plasma/(mmol/l), b = hemoglobin concentration in blood/(mmol/l), c = pH of plasma at 37 degrees C, d = base excess concentration in blood/(mmol/l). These two equations provide an arithmetic algorithm for calculation of the various acid-base variables of the blood after measuring the pH, the pCO2, and the hemoglobin concentration.
Scand J Clin Lab Invest Suppl 1977
PMID:The van Slyke equation. 1 78

Carriers of hemoglobin Providence have three types of beta chain in their hemolysates. The two abnormal chains have asparagine (Providence N, Prov N) or aspartic acid (Providence D) at position beta 82, instead of lysine. In vitro, only two beta chains are synthesized by reticulocytes of carriers, betaA and betaProv N. In vivo studies showed that the specific activity of Providence N was initially 10-fold higher than that of Providence D; the specific activities of the two labeled hemoglobins were approximately equal 5 wk after injection of isotope. Oxygen affinity of carriers' blood was somewhat increased, but they were not polycythemic. The affinity of the purified hemoglobins Providence was decreased. Addition of 2, 3 diphosphoglycerate had little effect on the affinity of either hemoglobin component, and addition of inositol hexaphosphate produced no change in the affinity of Providence D. These studies demonstrate that Providence N is deamidated to Providence D during the life span of the erythrocyte, and suggest this finding may represent only an easily observed prototype of posttranslational modification of proteins in general. Despite and abnormal P50 of the blood, oxygen transport is probably normal in carriers of the abnormal hemoglobins.
J Clin Invest 1977 Apr
PMID:Postsynthetic deamidation of hemoglobin Providence (beta 82 Lys replaced by Asn, Asp) and its effect on oxygen transport. 1 73

The kinetics of the cyanate-hemoglobin reaction in normal whole blood have been investigated. The mechanism was found to be second order, irreversible, bimolecular. The influence of the temperature, pH, Po2, and Pco2 on the reaction rate constant was examined. A temperature change from 37 degrees to 42 degrees C, resulted in a 50 percent increase in the rate constant. The rate constant increased in proportion to the pH decrease, and deoxygenated whole blood was carbamylated approximately twice as fast as oxygenated blood. Carbon dioxide pressures had no influence on rates of carbamylation when a constant pH was maintained. A maximum rate constant of 3.7 M-U min.-u was obtained with conditions which were compatible with the red blood cells. This knowledge of the reaction mechanism and the influence of important system parameters on the reaction rate constant may be applied to the development of an extracorporeal system for the treatment of sickle cell anemia.
J Lab Clin Med 1977 May
PMID:Kinetics of the cyanate-hemoglobin reaction in whole blood. 1 70

Hb G San Jose (beta7 glu leads to gly) was studied with respect to oxygen affinity, Bohr effect, surface activity in dilute aqueous solutions, mechanical precipitability, heat stability and its ability to copolymerize in the deoxy form with Hb S. Oxygen affinity, Bohr effect, and polymerization with Hb S were found to be identical to those of Hb A when studied under the same conditions. However, surface activity and mechanical precipitation rates of the oxyconformers closely resembled those of oxyhemoglobin S. Hb G San Jose was also found to be slightly more unstable with heat than Hb A, although the instability was not detected by the usual incubation method of 1 hr at 50 degrees and higher temperatures were needed to elicit this difference. It is concluded that the ability to polymerize and the presence of increased surface activity are distinct and separable attributes of hemoglobin mutants. The finding that mixtures of Hb S and Hb G San Jose gel like mixtures of Hb S and Hb A supports the conclusion that only one beta 6 Val combining site per tetramer is required for polymer formation.
J Lab Clin Med 1977 Nov
PMID:Some properties of Hb G San Jose (beta7 glu replaced by gly): comparisons with Hb S. 2 Apr 81


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