DETERMINATION OF THE NUCLEOTIDE CONFORMATION IN THE PRODUCTIVE ENZYME-SUBSTRATE COMPLEXES OF RNA-DEPOLYMERASES

The aim of this work is to determine the conformation of the nucleobas e adjacent to the cleavable phosphodiester bond in the productive enzy me-substrate complex of RNA-depolymerizing enzymes, To this end the ki netic parameters of hydrolysis of UpA, 2'-C-Me- and 3'-C-Me-UpA were d etermined for RNase A, RNase Pb-2, nuclease S-1 and snake venom phosph odiesterase, In these derivatives the ranges of the allowed orientatio n of uridine residues are restricted due to the substitution of methyl groups for the ribose hydrogen atoms, The results described demonstra te that the proposed method is of general value for the estimation of the nucleotide glycoside angles in the productive enzyme-substrate com plexes. (C) 1997 Federation of European Biochemical Societies.