DEPHOSTATIN, A NOVEL PROTEIN-TYROSINE-PHOSPHATASE INHIBITOR PRODUCED BY STREPTOMYCES .1. TAXONOMY, ISOLATION, AND CHARACTERIZATION

A novel inhibitor of protein tyrosine phosphatase, dephostatin, was isolated from the culture broth of a strain of Streptomyces. The active principle was extracted from the broth filtrate with ethyl acetate and purified by silica gel chromatography and by HPLC. Dephostatin inhibited protein tyrosine phosphatase prepared from a human neoplastic T-cell line with an IC50 at 7.7 muM. The inhibitory pattern of dephostatin was competitive against the substrate. Dephostatin inhibited the growth of Jurkat cells.