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CTP synthetase is an enzyme involved in pyrimidine biosynthesis that interconverts UTP and CTP. == Reaction mechanism == CTP synthetase catalyzes the last committed step in pyrimidine nucleotide biosynthesis: ATP + UTP + glutamine → ADP + Pi + CTP + glutamate It is the rate-limiting enzyme for the synthesis of cytosine nucleotides from both the ''de novo'' and uridine salvage pathways. The reaction proceeds by the ATP-dependent phosphorylation of UTP on the 4-oxygen atom, making the 4-carbon electrophilic and vulnerable to reaction with ammonia. The source of the amino group in CTP is glutamine, which is hydrolysed in a glutamine amidotransferase domain to produce ammonia. This is then channeled through the interior of the enzyme to the synthetase domain. Here, ammonia reacts with the intermediate 4-phosphoryl UTP. 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「CTP synthetase」の詳細全文を読む スポンサード リンク
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