Brdtain N - Terminal Sequences of a - Crystallin
نویسندگان
چکیده
The amino acid sequences at the N-terminal ends of the chains of the lens protein, a-crystallin, were studied. Both the main kinds of chain in bovine ix-crystallin (A chains and B chains) have an N-terininal methionine residue, and the amino group is acetylated. Selective purification of the peptides in a tryptic digest of bovirne a-crystallin gave a preparation consisting largely of the N-terminal peptide from the A chains, and the sequence of this peptide was elucidated. Subsequently, the N-terminal peptides were prepared from separated A and B chains. The proposed sequences are: A chain, acetyl-Met-Asp-Ile-Ala-Ile-Gln-His-Pro-TrpPhe-Lys; B chain, acetyl-Met-Asp-Ile-Ala-Ile-His-(Pro,Trp)-Ile-Arg. The similarity between the sequences supports the hypothesis that the A and B chains are derived evoltitionarily from a common precursor.
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