Studies on antibiotics from the genus Bacillus. X. The structure of brevistin.

Acid hydrolysis revealed the constituent amino acids by brevistin as follows: aspartic acid (D-form 2, L-form 1), L-threonine (1), glycine (1), sum of L-valine and L-isoleucine (1), L-phenylalanine (1), L-trytophan (1), and 2,4-diaminobutyric acid (D-form 1, L-form 1). The constituent fatty acid was elucidated to be anteisononanoic acid by gas chromatography-mass spectrometry. A lactone linkage was proved between phenylalanine and the hydroxy group of threonine. Opening the lactone ring with dilute alkali afforded brevistinic acid. Deacylation with an enzyme preparation, Polymyxin Acylase, gave deacyl brevistinic acid. Cleavage reaction with N-bromosuccinimide, sequential analysis by EDMAN degradation and some additional evidences clarified the total structure of brevistin.