CHEMICAL HETEROGENEITY OF HUMAN HEMOGLOBIN-F - DIRECT EVIDENCE FOR THE EXISTENCE OF 3 TYPES OF GAMMA-CHAIN, THE G-GAMMA-I, A-GAMMA-I, AND A-GAMMA-T CHAINS

Direct evidence is presented for the existence of three types of γ chain of human hemoglobin F. A modification of a CM-cellulose chromatographic method has allowed the incomplete separation of these γ chains while high pressure liquid chromatography and fingerprint analyses of tryptic peptides of zones of the isolated γ chains, and amino acid analyses of isolated peptides were used to identify the chains. These studies have shown that the presence of a glycyl residue in position 136 (Gγ chain) is directly related to that of an isoleucyl residue in position 75 (Iγ chain), thus indicating the existence of an GγI chain, and that the presence of an alanyl residue in position 136 (Aγ chain) can be related to that of an isoleucyl residue in position 75, thus suggesting the existence of an AγI chain. When the isoleucyl residue at position 75 is replaced by a threonyl residue, invariably it is related to the alanyl substitution at position 136 (AγT chain). These data support indirect evidence from case analyses and family studies which were published before, and indicate that the Tγ chain is an allele of the Aγ chain which should be renamed the AγT chain. © 1979.