翻訳と辞書 Words near each other ・ Ribophorin ・ Riboprobe ・ Riboque ・ Ribordone ・ Riboregulator ・ Ribose ・ Ribose 1,5-bisphosphate phosphokinase ・ Ribose 1-dehydrogenase (NADP+) ・ Ribose 5-phosphate ・ Ribose isomerase ・ Ribose repressor ・ Ribose-5-phosphate adenylyltransferase ・ Ribose-5-phosphate isomerase ・ Ribose-5-phosphate isomerase deficiency ・ Ribose-5-phosphate—ammonia ligase ・ Ribose-phosphate diphosphokinase ・ Riboside ・ Ribosomal binding site ・ Ribosomal DNA ・ Ribosomal frameshift ・ Ribosomal Intergenic Spacer analysis ・ Ribosomal L28e protein family ・ Ribosomal pause ・ Ribosomal protein ・ Ribosomal protein L10 leader ・ Ribosomal protein L13 leader ・ Ribosomal protein L19 leader ・ Ribosomal protein L20 leader ・ Ribosomal protein L21 leader ・ Ribosomal protein L4 Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Ribose-phosphate diphosphokinase ： ウィキペディア英語版 Ribose-phosphate diphosphokinase Ribose-phosphate diphosphokinase (or phosphoribosyl pyrophosphate synthetase or ribose-phosphate pyrophosphokinase) is an enzyme that converts ribose 5-phosphate into phosphoribosyl pyrophosphate (PRPP).〔〔 It is classified under . The enzyme is involved in the synthesis of nucleotides (purines and pyrimidines), cofactors NAD and NADP, and amino acids histidine and tryptophan, linking these biosynthetic processes to the pentose phosphate pathway, from which the substrate ribose 5-phosphate is derived. Ribose 5-phosphate is produced by the HMP Shunt Pathway from Glucose-6-Phosphate. The product phosphoribosyl pyrophosphate acts as an essential component of the purine salvage pathway and the de novo synthesis of purines. Dysfunction of the enzyme would thereby undermine purine metabolism. Ribose-phosphate pyrophosphokinase exists in bacteria, plants, and animals, and there are three isoforms of human ribose-phosphate pyrophosphokinase.〔 In humans, the genes encoding the enzyme are located on the X chromosome.〔 == Reaction mechanism == Ribose-phosphate diphosphokinase transfers the diphosphoryl group from Mg-ATP (Mg2+ coordinated to ATP) to ribose 5-phosphate.〔 The enzymatic reaction begins with the binding of ribose 5-phosphate, followed by binding of Mg-ATP to the enzyme. In the transition state upon binding of both substrates, the diphosphate is transferred. The enzyme first releases AMP before releasing the product phosphoribosyl pyrophosphate. Experiments using oxygen 18 labelled water demonstrate that the reaction mechanism proceeds with the nucleophilic attack of the anomeric hydroxyl group of ribose 5-phosphate on the beta-phosphorus of ATP in an SN2 reaction. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ribose-phosphate diphosphokinase」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.