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 of 1 gave Leu, Ile, Ser, Thr, and Asp moieties. ALthough 1 was a peptide compound, fragmentation by mild hydrolysis was not accomplished under any conditions. So, we performed the structure elucidation using various 2D NMR techniques. In the NMR studies, the addition of a small amount of trifluoroacetic acid gave relatively sharp and resolved signals, such that the structure of this novel cyclic lipodepsipeptide consisting of 11 amino acids and a 3-hydroxydecanoic acid moiety could be determined. Chirality of the constituent amino acids was analyzed by chiral HPLC, but two Asp residues could not be distinguished because they were contained as a racemic mixture. Finally, their chiralities were determined by NMR analysis of ¹³C-labeled 1 into which [L-¹³C]Asp had been biosynthetically incorporated.