CONFORMATION OF DCDP BOUND TO PROTEIN-R1 OF ESCHERICHIA-COLI RIBONUCLEOTIDE REDUCTASE

Deoxycytidine 5'-diphosphate (dCDP) is a product and competitive inhibitor of ribonucleoside-diphosphate reductase (EC 1.17.4.1) from Escherichia coli. Its conformation in the enzyme-bound state is of importance for understanding the reaction mechanism. Free and bound dCDP are in fast exchange and the transferred nuclear Overhauser effect in two-dimensional H-1 NMR was used to obtain information about interproton distances within bound dCDP. The results are consistent with a model of dCDP with the base in anti conformation and the sugar in S-type puckering, when bound either to the complete enzyme complex or to the large protein subunit alone. (C) 1994 Academic Press, Inc.