[Effect of guanine and guanosine-2',3' phosphate on sarcolysin-H3 binding to the DNA of rat liver].

Rats were injected sarcolysin-H3 in a dose of 200 or 500 mC per rat. In animals sacrificed 30, 60 and 90 minutes following sarcolysin-H3 injection an increased radioactivity of DNA was noted that indicates binding of sarcolysin-H3 or its labelled derivatives to DNA. Guanine or quanosine-2', 3' monophosphate injected in animals decreased binding of sarcolysin-H3 to the rat liver DNA (maximum reduction of DNA radioactivity in 47%). In the experiments in vitro guanosine-2', 3' phosphate inhibited sarcolysin-H3 binding to DNA isolated from E. coli. A protective effect of quanine and guanosine-2', 3' phosphate with respect to DNA alkylation seems to be considerably conditioned by a competitive action of these nucleophils.