L-Amino acid a-ligase (EC 6.3.2.28) catalyzed formation of a-peptide bond in unprotected L-amino acids in an ATP-dependent manner. BL00235 gene in Bacillus licheniformis NBRC12200 coded as a new L-amino acid ligase. BL00235 substrate specificity was strict; only methionine or leucine was acceptable as dipeptide N-terminal residues.