PHOLIPEPTIN, A NOVEL CYCLIC LIPOUNDECAPEPTIDE FROM PSEUDOMONAS-FLUORESCENS

An inhibitor of phosphatidylinositol-specific phospholipase C (PI-PLC) , pholipeptin (1), was purified from the culture broth of Pseudomonas sp. by solvent extraction and column chromatography. Acid hydrolysis o f 1 gave Leu, Ile, Ser, Thr, and Asp moieties. Although 1 was a peptid e compound, fragmentation by mild hydrolysis was not accomplished unde r any conditions. So, we performed the structure elucidation using var ious 2D NMR techniques. In the NMR studies, the addition of a small am ount of trifluoroacetic acid gave relatively sharp and resolved signal s, such that the structure of this novel cyclic lipodepsipeptide consi sting of 11 amino acids and a 3-hydroxydecanoic acid moiety could be d etermined. Chirality of the constituent amino acids was analyzed by ch iral HPLC, but two Asp residues could not be distinguished because the y were contained as a racemic mixture. Finally, their chiralities were determined by NMR analysis of C-13-labeled 1 into which [L-C-13]Asp h ad been biosynthetically incorporated.