其實這是初學生化者最感困擾的問題,這兩者都是合成的意思,但何時該用哪個字,目前判斷的原則如下:
1. 若聚合的反應中涉及ATP或三磷酸核苷酸的高能鍵,則用Synthetase。
所以Synthetase其實就是一種Ligase (連接酶)(第六類酵素)。
例如:
(1) acetyl~CoA synthetase (讓脂肪酸變成一隻"基",脂肪醯基)
(2) amino acyl tRNA synthetase (使free tRNA攜帶胺基酸)
(3) Gln synthetase
(4) Asn synthetase
(5) Carbamoyl phosphate synthetase I (in urea cycle) & II (in pyrimidine synthesis)
(6) Argininosuccinate synthetase (in urea cycle)
(7) PRPP synthetase (in nucleotide synthesis)
(8) Citidylate (CTP) synthetase (UTP氨化形成CTP)
2. 若聚合反應中不涉及高能鍵,則用Synthase。Synthase則屬於Lyase (裂解酶)(第四類酵素)。
例如:
(1) Citrate synthase (in TCA cycle)
(2) HMG~CoA synthase (in cholesterol synthesis)
(3) Glycogen synthase (in glycogenesis)
(4) δ-aminolevulinate synthase (動物體合成血質環途徑)
(5) fatty acid synthase complex
(6) Thymidylate synthase (由dUMP合成dTMP)
(7) Malate synthase (in Glyoxylate cycle)
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