Primary structures of alpha-crystallin A chains of elephant, whale, hyrax and rhinoceros

As part of a study of the evolutionary development of the eye lens protein alpha-crystallin the 173-residue A chain of this protein has been studied in elephant, whale, hyrax and rhinoceros. The primary structures were inferred mainly from amino acid compositions of peptides obtained by enzymic digestions and CNBr cleavage. The positions of substitutions, as compared to the known bovine A chain, were confirmed by Edman degradation. In accordance with the previously observed slow rate of evolution of the A chain only a small number of substitutions was found among these species. Elephant and hyrax share a number of unique substitutions, strongly indicating a common ancestry of these two species within the mammalian class.