The tryptic peptide composition of the beta chains of hemoglobins A and B of the Domestic cat (Felis catus)

The tryptic peptides from the betaA and betaB chains of cat hemoglobins A and B have isolated and the amino acid compositions determined. Differences between the two chains were found in two peptides, betaT-1 (Glylead toSer) and betaT-14 (Asnlead toSer and Lyslead toArg). The Glylead toSer and Lysleand toArg substitutions areplaced at beta-1 and beta-144 respectively from earlier work, and the third substitution, AsnleadSer at beta-139 is suggested from this work. in addition, the presence of a blocked amino terminus in betaB has been confirmed. Tentative sequences constructed by homology with known beta-chain structures suggest the occurrence of substitutions at alpha1beta1 contacts in betaA and betaB that may be functionally significant. There are at least 18 differences in amino acid composition between cat betaA and dog beta-chains and 22 differences between cat betaA and normal adult human beta-chains.