Crystalline Quinolinate Phosphoribosyltransferase

Quinolmate phosphoribosyltransferase catalyzes the formation of nicotinic acid mononucleotide, carbon dioxide, and inorganic pyrophosphate from quinolinic acid and 5-phosphoribosyl 1-pyrophosphate.The enzyme has a molecular weight of 165,000 and can be irreversibly dissociated into inactive protein units with a molecular weight of 54,000.TJn- like other reactions in which the enzymatic transfer of the phosphoribosyl group occurs, the kinetics of this reaction is consistent with the involvement of a ternary complex of enzyme, quinolinic acid, and 5-phosphoribosyl l-pyrophosphate.Attempts to show exchange reactions were unsuccessful.