Formation of deoxycytidine phosphates from cytidine phosphates in extracts from Escherichia coli.

Strong evidence has been obtained from experiments in viva that in different types of cells, deoxyribosyl compounds are formed through a reduction of the corresponding ribosyl compounds (cf. (1)). Recently, enzyme systems have been obtained from avian, mammalian, and bacterial cells, which carry out such transformations with pyrimidine and purine ribonucleotides (2-4). The present paper describes in detail our experiments with an extract from Escherichia coli which carries out the formation of deoxycytidine phosphates from cytidine monophosphate in the presence of adenosine triphosphate and Mg++ ions. Evidence will be presented for the proposition that the reduction of the ribonucleotide takes place at the diphosphate level, and that reduced triphosphopyridine nucleotide, directly or indirectly, is involved in this process. A preliminary account of this work has been published (2).