The number and nature of , -unsaturated amino acids in subtilin

In subtilin, a peptide produced by Bacillus subtilis, there are present three α,β-unsaturated amino acids, namely, two residues of dehydroalanine and one residue of β-methyldehydroalanine (dehydrobutyrine). Subtilin and nisin, a polypeptide produced by Streptococcus lactis, thus have in common not only the COOH-terminal sequence dehydroalanyllysine but also the number and nature of α,β-unsaturated amino acids.