Biopolymers and cell. 1988. Volume 4. № 6. 298 - 302

A. I. Zintchenko, L. A. Eroshevskaya, V. N. Barai, I. A. Mikhallopulo

SUBSTRATE SPECIFICITY OF URIDINE AND PURINE NUCLEOSIDE PHOSPHORYLASES OF THE ESCHER1CHIA COLI WHOLE CELLS

Summary

    Substrate specificity of uridine and purine nucleoside phosphorylases of the whole cells of Escherichia coli BM-11 has been studied monitoring phosphorolysis of uridine and a series of its analogues modified in the carbohydrate moiety to uracil and pentofuranose-I-phosphate, and synthesis of corresponding adenine nucleosides. Both enzymes reveal similar requirements to the structure and stereochemistry of uracil nucleosides and of the pentofuranose-1-phosphates, respectively, namely: a) modifications at C-3' decrease the substrate activity to a greater extent as compared with the same modifications at C-2'; the order of substrate activity in the case of modifications at C-2' and C-3' is OH> H> NH2> OH-ara (xylo)» 2'(3')-C-methyl; b) substitution of a methyl group for one of the protons at carbon atom of 5'-CH?OH group does not lead to an essential alterations of the substrate activity in such analogues in comparison with the natural substrates — uridine and ribofuranose-1-phosphate, respectively.