Biosynthesis of the Purines

A procedure for purification of formylglycinamide ribonucleotide amidotransferase from chicken liver has been presented. The highly purified preparation showed a single component in the ultracentrifuge. The molecular weight of the enzyme was found to be about 133,000 with a sedimentation coefficient of 6.5 S. The enzyme is rapidly denatured by alkaline or thermal treatment. This denaturation, however, is completely prevented by the addition of all of the substrates and cofactors of the enzyme and partially by various combinations of these substrates and cofactor. The equivalence of the products formed in the reaction catalyzed by the enzyme was studied by the use of various assay procedures. For the formation of 1 mole of formylglycinamidine ribonucleotide, a product of the reaction, 1 mole each of glutamine and of ATP was converted to glutamate and to ADP and orthophosphate, respectively.