Biomaterial Database

Uridine phosphorylase from Escherichia coli. Kinetic properties and mechanism. 1976

T A Krenitsky

Type I and Type II uridine phosphorylases (uridine: orthophosphate ribosyltransferase EC 2.4.2.3) are distinguished by their pH optima (Krenitsky et al. (1965) J. Biol. Chem. 240, 1281-1286). A Type I enzyme was partially purified from Escherichia coli. The crossing pattern of the initial velocity analysis indicated that the catalytic mechanism involved the sequential addition of substrates to the enzyme. Product inhibition by uracil or by ribose 1-phosphate was linear competitive with uridine or with concentrations of phosphate below 3 mM. This indicated that the sequence of substrate addition was random rather than ordered. At concentrations of phosphate above 3 mM, product inhibition by uracil was complex. The random mechanism of this Type I enzyme contrasts with the ordered mechanism of a Type II enzyme from rat liver (Kraut, A. and Yamada, E.W. (1971) J. Biol. Chem. 246, 2021-2030).

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010430	Pentosyltransferases	Enzymes of the transferase class that catalyze the transfer of a pentose group from one compound to another.
D010710	Phosphates	Inorganic salts of phosphoric acid.	Inorganic Phosphate,Phosphates, Inorganic,Inorganic Phosphates,Orthophosphate,Phosphate,Phosphate, Inorganic
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D014498	Uracil	One of four nucleotide bases in the nucleic acid RNA.
D014529	Uridine	A ribonucleoside in which RIBOSE is linked to URACIL.	Allo-Uridine,Allouridine,Allo Uridine
D014543	Uridine Phosphorylase	An enzyme that catalyzes the transfer of ribose from uridine to orthophosphate, forming uracil and ribose 1-phosphate.	5-Fluoro-2'-deoxyuridine Phosphorylase,5 Fluoro 2' deoxyuridine Phosphorylase,Phosphorylase, 5-Fluoro-2'-deoxyuridine,Phosphorylase, Uridine