The occurrence of several kinds of haemoglobin in human blood

The metamorphosis of hemoglobin in the bullfrog

1. Tadpole and adult hemoglobin do not differ significantly in molecular weight. The molecular weight of both is in the neighborhood of 68,000. 2. Heme-heme interaction as measured by the value of n in Hill's equation is virtually the same-about 2.8-in both tadpole and adult. 3. There appears to be no significant effect of pH upon the oxygen equilibrium of tadpole hemoglobin, in contrast to large Bohr and reverse Bohr effects in the adult. This is taken to mean that during metamorphosis acid groups of globin become sensitive to the oxygenation of heme by some change in the mode of linkage between heme and globin. 4. The oxygen affinity of tadpole hemoglobin is about seven times as great as that of the adult at pH 6 and twice as great at pH 9.

The development of an acquired haemoglobin abnormality caused by thermal injury

Alkali denaturation of the haemoglobin derived from burned patients at various intervals from the time of the injury was investigated. A delayed denaturation curve was always found. The involvement of the transfused cells was established by a differential agglutination technique. Red cell populations were fractionated into two portions, one of which was probably enriched in younger cells. This portion was preferentially affected.A starch gel technique yielded a "slow" and a "fast" fraction of haemoglobin with differing denaturation rates, even in normals. The "slow" fraction appeared to be increased quantitatively and qualitatively, if compared with normal blood.

Foetal erythrocytes exhibit an increased ability to scavenge for nitric oxide

The presence of adult human whole blood inhibited in vitro relaxations of rat aortic rings by the nitric oxide (NO) donor S-nitroso-N-acetyl-DL-penicillamine (SNAP). Incubation with foetal blood containing the same concentration of haemoglobin produced a shift to the right of the relaxation curve. SNAP-induced vasorelaxations were more inhibited by dialysed solutions of haemoglobin than by the presence of erythrocytes in the organ bath, but there were no differences between the effect of adult or foetal haemoglobins. The presence of plasma from adult or foetal blood did not modify the effects of SNAP. Relaxations induced by endogenous, endothelium-derived, NO were more inhibited by foetal than by adult erythrocytes. These results suggest that foetal erythrocytes have a higher NO scavenging effect than those present in adult blood.

A comparative X-ray study of foetal and adult sheep haemoglobins

Haemoglobins from adult sheep and from foetuses of different ages were crystallized, using a standard procedure. The optical properties, cell dimensions and space-groups of the wet and, where possible, of the air-dried crystals were determined, and surveys were made of the lower order diffraction patterns in each of the principal crystal zones. The results obtained provide additional evidence for the non-identity of the foetal and adult haemoglobins and lead to certain conclusions relevant to the general problem of haemoglobin structure. Methaemoglobin from foetuses aged less than 120 days was found to crystallize in either of two forms, each of which was different from methaemoglobin crystals of adult sheep pre­pared by the same method. Haemoglobin from later foetuses is difficult to crystallize, and its properties resemble those of artificial mixtures of adult and early foetal haemoglobins. No general picture of the structural differences between adult and foetal haemoglobin has emerged from this study, mainly because these were obscured by differences in molecular packing. Indications were found of a difference in molecular symmetry between these two proteins, and this could be correlated with different splitting properties in solution. There is also evidence of a pronounced intramolecular layering in foetal haemoglobin. A new method of controlled shrinkage of protein crystals at constant humidity was developed and applied to foetal haemoglobin crystals, which were shown to pass through a series of at least four well-defined lattices. The densities of wet adult and foetal haemoglobin crystals were measured and used for the estimation of ‘bound water’. The amounts of ‘bound water’ were of the same order as those obtained from haemoglobin crystals of other species.

Adult hemoglobin synthesis by reticulocytes from the human fetus at midtrimester

The synthesis of adult-type hemoglobin was measured in small samples of peripheral blood cells from 9- to 18-week human fetuses. Hemoglobin indistinguishable from hemoglobin A was identified by ion-exchange chromatography, electrophoresis at pH 8.6, tryptic peptide analysis, and the insensitivity of its synthesis to the action of O-methylthreonine. Synthesis of hemoglobin A accounted for 8 to 14 percent of total hemoglobin synthesis and was demonstrated in as little as 10 microliters of fetal blood. These studies provide sensitive methods for the detection of beta chain types in hemoglobin synthesized by the human fetus at midtrimester. If methods to obtain small quantities of fetal blood at midtrimester become available, these techniques should be applicable to the antenatal detection of sickle cell anemia and related hemoglobinopathies.

Electrophoretic studies of red cell extracts of stored blood

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A review of the varieties of human haemoglobin in health and disease

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