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Results for “HEMOGLOBIN”

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At least 145 records · Page 8Linked to original sources

PubMed1992

Regeneration of functional hemoglobin from iron(III) hemoglobin by reduction with hydrogen and a heterogeneous catalyst.

Functional hemoglobin was regenerated from partially autoxidized hemoglobin by reduction with molecular hydrogen in the presence of a heterogeneous catalyst consisting of elemental platinum embedded in an electroactive polymer. The visible spectrum of the regenerated hemoglobin was identical to that of native iron(II) hemoglobin. The regenerated hemoglobin displayed highly cooperative oxygen-binding characteristics. P50 values for oxidized-regenerated hemoglobin samples were not different from native hemoglobin. The Hill coefficients for regenerated hemoglobin were slightly lower than the controls, possibly because of small amounts of irreversibly oxidized hemoglobin arising during the initial autoxidation. The advantages of the reduction system include: (1) the heterogeneous catalyst avoids the problem of protein adsorption onto bare platinum, (2) catalyst and reducing agent are easily removed from the protein, and (3) the by-product H+ is buffered easily.

Buffers↗

PubMed1988

Influence of ligation state and concentration of hemoglobin A on its cross-linking by glycolaldehyde: functional properties of cross-linked, carboxymethylated hemoglobin.

The ligation state of hemoglobin during its cross-linking by glycolaldehyde influences the ultimate oxygen affinity of the cross-linked protein. Thus, if the cross-linking is performed with carbonmonoxy-hemoglobin, the oxygen affinity increases slightly to a P50 of 7 mmHg from a P50 of 9 mmHg for unmodified hemoglobin. In contrast, when deoxyhemoglobin is cross-linked with glycolaldehyde, the oxygen affinity of the product decreases (P50 = 15 mmHg). When deoxyhemoglobin is first carboxymethylated and then cross-linked with glycolaldehyde, an even lower oxygen affinity is achieved (P50 = 23 mmHg). Carboxymethylated hemoglobin is very responsive to the presence of 5% CO2 with a P50 of 33 mmHg, which is lowered further to 42 mmHg when chloride (0.1 M) is also present. Hemoglobin carboxymethylated and cross-linked under anaerobic conditions is also responsive to the modulators CO2 and chloride with a resultant oxygen affinity of 27 mmHg. The type of cross-linking of liganded hemoglobin by the mild reagent glycolaldehyde is dependent upon the initial hemoglobin concentration. Thus, with dilute hemoglobin (45 microM in tetramer), cross-linking by glycolaldehyde (50 mM) results in about 75% of 64,000 molecular weight species (some of which are cross-linked within tetramer) and 25% of intertetrameric cross-linked species with a range of molecular weights averaging 128,000-512,000. With hemoglobin solutions of higher concentration (360 microM), the amount of the higher molecular weight species increases to about 65% with a corresponding reduction to 35% in the 64,000 molecular weight component.

Acetaldehyde↗

PubMed2000

Substitution of the heme binding module in hemoglobin alpha- and beta-subunits. Implication for different regulation mechanisms of the heme proximal structure between hemoglobin and myoglobin.

In our previous work, we demonstrated that the replacement of the "heme binding module," a segment from F1 to G5 site, in myoglobin with that of hemoglobin alpha-subunit converted the heme proximal structure of myoglobin into the alpha-subunit type (Inaba, K., Ishimori, K. and Morishima, I. (1998) J. Mol. Biol. 283, 311-327). To further examine the structural regulation by the heme binding module in hemoglobin, we synthesized the betaalpha(HBM)-subunit, in which the heme binding module (HBM) of hemoglobin beta-subunit was replaced by that of hemoglobin alpha-subunit. Based on the gel chromatography, the betaalpha(HBM)-subunit was preferentially associated with the alpha-subunit to form a heterotetramer, alpha(2)[betaalpha(HBM)(2)], just as is native beta-subunit. Deoxy-alpha(2)[betaalpha(HBM)(2)] tetramer exhibited the hyperfine-shifted NMR resonance from the proximal histidyl N(delta)H proton and the resonance Raman band from the Fe-His vibrational mode at the same positions as native hemoglobin. Also, NMR spectra of carbonmonoxy and cyanomet alpha(2)[betaalpha(HBM)(2)] tetramer were quite similar to those of native hemoglobin. Consequently, the heme environmental structure of the betaalpha(HBM)-subunit in tetrameric alpha(2)[betaalpha(HBM)(2)] was similar to that of the beta-subunit in native tetrameric Hb A, and the structural conversion by the module substitution was not clear in the hemoglobin subunits. The contrastive structural effects of the module substitution on myoglobin and hemoglobin subunits strongly suggest different regulation mechanisms of the heme proximal structure between these two globins. Whereas the heme proximal structure of monomeric myoglobin is simply determined by the amino acid sequence of the heme binding module, that of tetrameric hemoglobin appears to be closely coupled to the subunit interactions.

Chromatography, Gel↗

PubMed1992

Evolution of ruminant hemoglobins. Thermodynamic divergence of ox and buffalo hemoglobins.

The ligand-binding properties of hemoglobins from two homozygote phenotypes (AA and BB) of water buffalo (Bubalus bubalis) have been characterized by equilibrium and kinetic techniques. In the case of the BB phenotype, the two constituent hemoglobins have been purified and separately analysed. Buffalo hemoglobins display the reduced sensitivity to organic phosphates characteristic of ruminant hemoglobins, their physiological effector probably being the chloride ion. In contrast to the other known hemoglobins from ruminants, all the hemoglobins from the water buffalo display a significant temperature sensitivity, the delta H for oxygen binding in the presence of physiological effectors approaching that of human hemoglobin (delta H = -30.5 kJ/mol O2). This discrepancy with the other ruminant hemoglobins (e.g. ox, delta H = -10.4 kJ/mol O2), whose primary structure is very similar to that of buffalo, hemoglobins might be correlated to the different habitat and phylogenetic history of the two subfamilies (Bos and Bubalus) of Bovidae.

Animals↗

PubMed1975

Cross-linking of hemoglobin, haptoglobin, and hemoglobin-haptoglobin complex with bifunctional imidoesters.

Dimethyl adipimidate was used to cross-link the polypeptides within hemoglobin, haptoglobin, and hemoglobin-haptoglobin complex. Cross-linked hemoglobin retained considerable ability to bind haptoglobin, although the amounts bound were reduced and the haptoglobin reaction could be used to fractionate the modified hemoglobin. With cross-links limited to intramolecular sites, hemoglobin showed four bands on polyacrylamide gel electrophoresis in sodium dodecyl sulfate, identified, with reference to the subunit polypeptides, as monomer, dimer, trimer, and tetramer. The dimer region consisted of at least two separable species. When hemoglobin-haptoglobin complex was cross-linked, a band of hemoglobin dimer was present, which demonstrates that at least two hemoglobin subunits have a close spatial relation when bound to haptoglobin. Some comparisons with adipimidate-reacted hemoglobin were made using malonimidate and suberimidate and some marked differences were noted.

Animals↗

PubMed1979

Glycosylated hemoglobins: increased glycosylation of hemoglobin A in diabetic patients.

The components of the hemoglobin-A1 fraction--hemoglobins A1a--c--arise from nonenzymatic glycosylation of hemoglobin A at the beta-chain N-terminal amino groups and can be resolved from hemoglobin A by cation exchange chromatography. Glycosylation can also occur at the alpha-chain N-terminals as well as the epsilon-amino groups of lysine residues of both alpha- and beta-chains; this results in glycosylated species appearing in the hemoglobin-A fraction. In this study, we determined the extent of hemoglobin-A glycosylation using a colorimetric chemical method specific for the detection of ketoamine-linked hexoses in proteins. We demonstrate increased glycosylation of the main hemoglobin-A fraction in diabetic patients, which correlates significantly (r = 0.72, P less than 0.001) with the hemoglobin-A1 percentage determined by column chromatography in the corresponding hemolysates. This finding provides the basis for the application of this chemical procedure to the measurement of total glycosylation of hemoglobin.

Chemical Phenomena↗

PubMed2007

Is it necessary to consider obesity when constructing norms for hemoglobin or when screening for anemia using hemoglobin levels?

OBJECTIVE: To assess the relationship of total adiposity and abdominal adiposity on hemoglobin levels in Saudi nonpregnant women. METHODS: We carried out this cross-sectional study during winter of 2002 (from January to March) in and around Abha city, Kingdom of Saudi Arabia. Included in the study were 530 non-pregnant women between the age of 18-65 years. Body weight was measured using an Avery Beam weighing scale, while height was measured using a stadiometer and waist circumference using a fiberglass. Hemoglobin levels were estimated using cyanmethemoglobin method. Total obesity was defined as body mass index (BMI) >or=30 and abdominal obesity as WC >88 cm. RESULTS: The mean and median hemoglobin levels were significantly higher in abdominally obese women compared with totally obese (p<0.04 versus <0.02) and non obese ones (p<0.04 versus <0.03). No significant differences in the mean and median hemoglobin levels were observed when abdominally obese women were compared with both abdominally and totally obese ones (p<0.7 for both). The mean and the median hemoglobin levels were virtually identical in non-obese and totally obese women. Statistical analysis showed that the mean hemoglobin level was positively and significantly associated with WC (p<0.005) and negatively and insignificantly associated with BMI (p<0.8). CONCLUSION: In view of the positive and significant association between abdominal obesity and the mean hemoglobin level in this population, abdominal obesity should be considered when constructing norms for hemoglobin or when screening for anemia using hemoglobin levels.

Adolescent↗

PubMed1985

Relative rates of fetal hemoglobin and adult hemoglobin synthesis in cord blood of infants of insulin-dependent diabetic mothers.

Erythrocytosis, extramedullary erythropoiesis, and increased levels of plasma erythropoietin have been observed in newborn infants of diabetic mothers. Because there is evidence that there is a relationship between increased fetal hemoglobin production and acute erythropoietic expansion, it was considered important to study the proportion of fetal hemoglobin and adult hemoglobin synthesis in newborn infants of insulin-dependent diabetic mothers. Samples from nine newborn infants of diabetic mothers as well as nine control infants, ranging from 36 to 38 weeks of gestation, were incubated in an amino acid mixture containing [14C]leucine. The adult hemoglobin and fetal hemoglobin were then separated by column chromatography on DEAE [O-(diethylaminoethyl)] Sephadex. To confirm that the fetal hemoglobin obtained after Sephadex chromatography was not contaminated with other hemoglobins, several of the DEAE separations from each group were reconstituted and subjected to polypeptide chain elution using carboxyl-methyl cellulose chromatography. The data demonstrated that the newborn infants of diabetic mothers are synthesizing significantly more fetal hemoglobin than is expected for their period of development (82.2 +/- 3.6 v 72.8 +/- 4.2; P less than .005). It is suggested that the in utero environment of the fetus of the diabetic mother causes an increase in fetal hemoglobin synthesis.

Diabetes Mellitus, Type 1↗

PubMed1973