HETEROGENEITY OF FETAL HEMOGLOBIN OF GOAT

The heterogeneity of the goat fetal hemoglobin, which has been observed by measurements of the rate of denaturation in an alkaline medium, was reinvestigated. Analyses of the amino acid compositions of various peptides isolated from a tryptic digest of the γ chain failed to demonstrate a molecular heterogeneity. Alkali-induced denaturation rates of red cell hemolysates from normal newborn goats, and from newborn goats with a heterozygosity or homozygosity for the HbIαB allele, indicated the presence of two distinct components in each of these hemolysates. Similar experiments with isolated fetal hemoglobins containing either IαB or IIα polypeptide chains gave distinctly different denaturation curves, which obeyed first order kinetics. It was concluded that the presence of two structurally different α chains, which are the products of non-allelic structural genes, is responsible for the observed phenomenon; the differences in rate of alkali-induced denaturation apparently result from differences in the stability of the IIαγ and Iαγ dimer subunits. © 1969.