| Popis: |
The effect of the bleomycin A5 residue linked to four-, eight-, and twelve-mer oligodeoxyribonucleotides on the substrate properties of their tandem and continuous (with or without unmodified octanucleotide effectors) hybrid duplexes was studied using E. coli RNase H. The bleomycin derivatives of oligodeoxyribonucleotides were shown to form hybrid duplexes with practically the same thermostability as those formed by unmodified oligodeoxyribonucleotides. The RNA in the bleomycin-containing hybrid duplexes is cleaved by the E. coli RNase H; however, the initial hydrolysis rate (v0) is 2.6-3.4-fold reduced for the continuous duplexes. In the case of tandem hybrid complexes, the effect of bleomycin on v0 was less pronounced. We hypothesized that steric factors play a key role in the bleomycin inhibition and effectors probably determine the substrate properties of such hybrid complexes. Of all the tandem systems studied, the RNA duplex with the bleomycin-containing tetranucleotide flanked with two effectors displayed the best substrate properties. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2002, vol. 28, no. 4; see also http://www.maik.ru. |
