Differences in Affinity of Variant β Chains for a Chains: A Possible Explanation for the Variation in the Percentages of β Chain Variants in Heterozygotes

Abstract

The a and β chains of the hemoglobins A, S, Leslie and N-Baltimore have been isolated as PMB derivates by CM-cellulose and DEAE-cellulose chromatography. The relative affinities of the β^A, β^s, β^Leslie and β^N-Baltimore chains for α chains were measured through quantitation by chromatography of Che hemoglobins A and Leslie, A and S, and A and N-Baltimore that were formed when variable amounts of α chains were added to a mixture of equal amounts of the appropriate β chains. The data indicate a greatly decreased affinity of β^Leslie chains for a chains; a similar preference of a chains for β^A chains was observed for mixtures Involving α, β^A, and β^s chains, but the affinity of β^s chains for a chains was higher than that of β^Leslie chains. The _βN-Baltimore chains assembled with a chains at a similar rate as β^A chains. The data as Interpreted Indicate that the affinity of certain β chains for a chains can be a major post-translatlonal control mechanism which regulates the level of a β chain variant in heterozygotes.