Buffalo alpha S1-casein; its terminal residues and amino acid composition

Buffalo alpha S1-casein was treated with carboxypeptidase-A to determine the C-terminal amino acid residue, which was - leucine-tryptophan. The Sakaguchi reagent was used to confirm arginine as the N-terminal amino acid. The colored p-phenylazophenyl thiohydantoins of tryptophan and arginine released from C- and N-terminals respectively were quantitatively estimated and from this molecular weights of buffalo alpha S1 casein were calculated and found to be 26,300 and 26,100 respectively.