Study of Structural-Functional Organization of Nucleoside Phosphorylases of Gammaproteobacteria. Special Aspects of Functioning of Uridine Phosphorylase Phosphate-Binding Site.

Series of mutant genes of prokaryotic uridine phosphorylases (Shewanella oneidensis MR-1, Escherichia coli) were constructed, and the resulting strains-producers of the corresponding proteins were obtained. Proteins were purified, and their physicochemical and fermentative properties were studied. On the basis of the obtained data, the role of individual amino acid residues of the polypeptide chain of uridine phosphorylases in the formation and functioning of the phosphate-binding site in these proteins was shown. The assumption of independent binding of two substrates, ion of inorganic phosphate (Pi) and uridine (Urd), by nucleoside phosphorylases, was made. [ABSTRACT FROM AUTHOR]