[Ala4]Surfactin, a Novel Isoform from Bacillus subtilis Studied by Mass and NMR Spectroscopies

Abstract

When Bacillus subtilis S 499 was grown on a culture medium containing L‐alanine as nitrogen source, a mixture of surfactins was obtained. Suitable chromatographic conditions allowed the separation of isoforms. Among these compounds, a new variant of surfactin was isolated and its structure was established by chemical and spectrometric methods, especially by NMR spectrometry. It contains a peptide sequence which differs from that of standard surfactin by the replacement of the L‐valine residue by L‐alanine residue in position 4. The folding mode of [Ala4]surfactin as deduced from NMR results was compared with that of standard surfactin and the structure/properties relationship issuing from the study of this new isoform is discussed. Copyright © 1994, Wiley Blackwell. All rights reserved