The structures of katanosins A and B.

1H and 13C NMR studies on katanosin A confirmed the presence of eight usual amino acid residues which were previously deduced by amino acid analysis and suggested the presence of beta-hydroxyaspartic acid, beta-hydroxyleucine and beta-phenylserine residues. These amino acids were isolated and confirmed, including their stereochemistries, by comparison with the respective authentic specimens. Stereochemistries of the usual amino acids were determined by comparing the L-leucylated amino acids with reference compounds by HPLC. Lithium borohydride reduction and chromic acid oxidation of katanosin A and alkali-treated katanosin A elucidated a lactone linkage between the C-terminal Ser and phenylserine residues. Edman degradation on alkali-treated katanosin A clarified the total amino acid sequence. The difference in katanosins A and B was determined to be replacement of Val in A by Ile in B. Thus, the structures of katanosins A and B were elucidated.