1513-DMIA AND 1513-DMIB, DNA METHYLTRANSFERASE INHIBITORS PRODUCED BYSTREPTOMYCES SP. STRAIN NO 1513

Two new methyltransferase inhibitors were isolated from the culture fi ltrate of Streptomyces sp. strain No. 1513 and named 1513-DMIa and 151 3-DMIb. 1513-DMIa and 1513-DMIb were distinguished in certain properti es from DMI-1, DMI-2; DMI-3 and DMI-4 previously reported. The molecul ar weight of 1513-DMIa and 1513-DMIb were estimated to be 576 and 8400 from the results of FAB-MS and gel filtration, respectively. The inhi bitory activities of 1513-DMIa and 1513-DMIb were shown to be pH-and t emperature-dependent and both inhibited M. EcoRI in an uncompetitive m anner with respect to DNA or S-adenosylmethionine (SAM).