Observations on the structure of bacilysin

Abstract

Elementary analysis and other properties of a highly purified preparation of bacilysin indicated that a possible molecular formula for the substance is C12H18N2O5. The results of electrometric titration were consistent with the hypothesis that the substance was a peptide containing one free [alpha]-amino group and one free carboxyl group. Hydrolysis of bacilysin with 6N-hydrochloric acid at 105[degree] yielded L-alanine and L-tyrosine, but the ultraviolet spectrum of the substance showed that no tyrosine residue was present in the molecule and a nuclear-magnetic-resonance spectrum indicated that olefinic and aromatic protons were absent. The dini-trophenyl (DNP) derivative of bacilysin yielded DNP-alanine on acid hydrolysis. Bacilysin was hydrolysed by leucine aminopeptidase (EC 3.4.1.1) and by Pronase to give alanine and an uncharacterized amino-acid. Its infrared spectrum was consistent with the presence of a peptide grouping in the molecule. The optical rotatory dispersion of bacilysin and its reaction with thiosemicarbazide indicated that the substance contained an aldehyde or ketone group. Its behaviour on catalytic reduction and its reaction with sodium thiosulphate and with certain thiols suggested that an epoxide group was present. A possible type of structure for bacilysin is considered in the light of its known properties.