Crystalline Quinolinate Phosphoribosyltransferase from Alcaligenes eutrophus subsp. quinolinicus: Characteristic Properties and Chemical Modifications

Abstract

The effects of quinolinic acid analogues and 5-phosphoribosyl-l-pyrophosphate analo-gues on the activity of quinolinate phosphoribosyltransferase (EC 2.4.2.19) crystallized from Alcaligenes eutrophus subsp. quinolinicus have been investigated. Sugar and metal contents, amino acid composition and active site of the crystalline enzyme were also examined. The C-2 carboxyl group and pyridine ring of quinolinic acid and 5-phosphate of 5-phospho-ribosyl-l-pyrophosphate took part in the binding to the enzyme. This enzyme did not contain metal and was found to contain sugar about 1% as mannose. The amino acid composi-tion of this enzyme was compared with that of hog liver enzyme. Sulfhydryl, amino and imidazole groups may exist in the active site of the enzyme.