Cytotoxic effect of structurally modified bull seminal ribonuclease (AS RNase)

Chemical modifications of bull seminal ribonuclease (AS RNase) cause considerable changes in its cytotoxic activity. However, binding of AS RNase on cells has been changed little or not at all. Every modification (oxidation, reduction, carbomethylation, succinylation and maleylation) inhibited ribonuclease and aspermatogenic and embryotoxic activity of AS RNase. The common cytotoxic effect was also changed to some degree. Inhibition of incorporation of ³H-thymidine to BP-8 tumor cells in culture was observed after application of native, oxidized, reduced, and carboxymethylated AS RNase.