THE STRUCTURE OF OCTAPEPTIN D

STUDIES ON ANTIBIOTICS FROM THE GENUS BACILLUS. XXVIII)

Abstract

Amino acid analysis of the acid hydrolyzate of octapeptin D revealed the amino acid composition. These amino acids were converted to L-leucyl-derivatives and analyzed by high performance liquid chromatography to clarify their chiralities. These were determined to he: 2, 4-diaminobutyric acid (4L), Ser (D), Leu (2L, 1D). Deacylation with polymyxin acylase afforded deacyl octapeptin D. EDMAN degradation on deacyl octapeptin D revealed the N-terminal amino acid. Application of the chemical cleavage reaction for fragmentation of seryl peptides on tri (DNP)-octapeptin D afforded a DNP-heptapeptide, whose sequence was clarified by EDMAN degradation. Octapeptin D was separated into four components (D₁ D₂, D₃ and D₄) by high performance liquid chromatography. All the components were examined for their amino acid and fatty acid compositions. From the results, the structures of octapeptins D₁, D₂, D₃ and D₄ were determined.