查看文章

Fast non-covalent interactions of 16S rRNA Escherichia coli with 14C labeled 2', 3'-O-[4-N-(2-chloroethyl)-N-methylamino] benzylidene derivatives of deoxyribooligonucleotides d (pACCTTGTT) rA, d [pTTACGATC) rU, d (pTTTGCTCCCC) rA (less than [14C] CHRCl-reagents) observed at 0 degrees C were investigated. It was shown, that 16S rRNA and [14C] CHRCl-reagents at 0 degrees C form stable complexes which can not be disrupted under mild acidic conditions (pH 4, 40 degrees C) and under denaturing conditions (7 M urea, 50 degrees C), but are completely disrupted in the course of centrifugation in sucrose density gradient in the presence of SDS. Formation of such complexes of 16S rRNA with greater than [14C] CHRCl-reagents at 0 degrees C was observed due to the presence in the reagent preparation of a number of unidentified products, formed in the course of the synthesis of benzylidene derivatives, and having a hydrophobicity larger, than those for greater than CHRCl-derivatives of deoxyribooligonucleotide. Preparation of [14C] CHRCl-reagents, subjected for purification by reverse-phase chromatography, were unable to form such a complex with 16S rRNA at 0 degrees C. Studies on the complementary addressed modification at 0 degrees C (or incubation at 0 degrees C) with the use of the oligonucleotide benzylidene derivatives not purified from hydrophobic contaminations may lead to alkylation within these complexes during subsequent treatments and in such a way give incorrect information about the level of alkylation within the complex under investigation.