Deoxyribonuclease inhibitors produced by streptomycetes

Streptomyces sp. strain No. A-5838 produces three types of inhibitors of DNase II. Two of them, DNI-2 and DNI-3, were distinguished from the previously reported DNase II inhibitors, 5838-DNI and 5923-DNI, by their inhibitory profiles towards phosphodiesterases. DNI-2 has M(r) 654, and is considered to be a coproporphyrin. DNI-3 is an acidic substance with M(r) about 60,000 as estimated by gel filtration. The inhibitory activities of both inhibitors were shown to be temperature-dependent whereas only that of DNI-2 was pH-dependent.