Objective: To analyze the impact of mRNA expression of oral fluoropyrimidine (S-1) metabolism (thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyltransferase [OPRT]), on treatment outcomes in locally advanced gastric cancer patients receiving preoperative S-1 combined with oxaliplatin chemotherapy. Methods: Preoperative stage III gastric ca...

Complex U is composed of orotate phosphoribosyltransferase (EC 2.4.2.10) and orotidine-5’-phosphate decarboxylase (EC 4.1.1.23), the last two enzymes of the de nouo pathway for pyrimidine biosynthesis. Since the two enzymes have proved inseparable so far, the equilibrium constant for the phosphoribosyltransferase activity has been determined under conditions where the decarboxylase activity was...

The mutation in a young gouty male with a partial deficiency of hypoxanthine-guanine phosphoribosyltransferase has been evaluated. The serum uric acid was 11.8 mg/100 ml, and the urinary uric acid excretion was 1,279 mg/24 h. Erythrocyte hypoxanthine-guanine phosphoribosyltransferase was 34.2 nmol/h/mg, adenine phosphoribosyltransferase was 36.5 nmol/h/mg and phosphoribosylpyrophosphate was 2.6...

A uracil phosphoribosyltransferase (UMP-pyrophosphorylase) was found in several angiosperms and was partially purified from epicotyls of pea (Pisum sativum L. cv. Alaska) seedlings. Its pH optimum was about 8.5; its required approximately 0.3 mm MgCl(2) for maximum activity but was inhibited by MnCl(2); its molecular weight determined by chromatography on Sephadex G-150 columns was approximatel...

1. The hypoxanthine/guanine and adenine phosphoribosyltransferase activities in a wide variety of human tissues were studied during their growth and development from foetal life onward. A wide range of activities develop after birth, with especially high values in the central nervous system and testes. 2. Postnatal development of hypoxanthine/guanine phosphoribosyltransferase was also defined i...

Aim of this study was to ascertain whether allopurinol, usually administered to hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficient patients, or metabolites abnormally increased in HPRT deficient erythrocytes (NAD, PPribP) could be directly responsible for the reported increased activities of nicotinic acid phosphoribosyltransferase (NAPRT) and NADsynthetase (NADs) in these patients...

The structural requirements for the binding of purines to adenine phosphoribosyltransferase from monkey liver were explored by the determination of the K; values for 67 purines and purine analogues. Adenine was bound 40 times better than the most effectively bound analogues. Substitutions on the 6-amino group of adenine decreased binding to varying degrees. The hydroxylaminoand hydrazinopurines...