6533b85bfe1ef96bd12bb320

RESEARCH PRODUCT

Chromatographic and mass spectrometric characterization of the structures of the polypeptide antibiotics samarosporin and stilbellin and identity with emerimicin

subject

description

The structural identity of the polypeptide antibiotics, samarosporin I(II) and stilbellin I(II) with emerimicin IV(III) has been established by thin-layer chromatography, quantitative amino acid analysis by ion-exchange chromatography, gas-liquid chromatography of the N-pentafluoropropionyl amino acid n-propyl esters and N,O-bis-pentafluoropropionyl phenylalaninol with quartz capillaries coated with the chiral stationary phase N-propionyl-L-valine-tert-butylamide, and determination of the relative molecular masses and sequence-specific fragments by field desorption fast atom bombardment mass spectrometry. The separation of closely related sequence analogues of the above polypeptides could be achieved by reversed-phase high-performance liquid chromatography with spherical, fully porous octadecylsilyl bonded phases, and 86% aqueous methanol as eluent. The application of both chromatographic and mass spectrometric methods is demonstrated to be most valuable for the characterization of antibiotics with the unusual constituents α-aminoisobutyric acid, isovaline and phenylalaninol. The methology employed is regarded to be applicable to all polypeptide antibiotics of the peptaibol class.