討論:底物水平磷酸化
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未翻譯內容
編輯未翻譯內容如下：--Flame 歡迎泡茶 2011年5月14日 (六) 00:23 (UTC)
ATP is generated in a following separate step (key difference from oxidative phosphorylation) by transfer of the 高能磷酸 on 1,3-二磷酸甘油酸 to ADP via the enzyme 磷酸甘油酸激酶, generating 3-phosphoglycerate. As ATP is formed of a former anorganic phosphate group, this step leads to the energy yield of glycolysis.
The second Substrate-level phosphorylation occurs later by means of the reaction of phosphenolpyruvate (PEP)to pyruvate via the pyruvate kinase. This reaction regenerates the ATP that has been used in the preparatory phase of glycolysis to activate glucose to glucose-6-phosphate and 果糖-6-磷酸 to 果糖-1,6-二磷酸, respectively.
Once the 丙酮酸product of 糖酵解is moved to the mitochondrial matrix, the pyruvate is converted to acetate and binds 輔酶A to form Acetyl CoA to enter the 三羧酸循環 cycle. While the Krebs cycle is oxidative respiration, one more instance of 底物水平磷酸化 occurs as 鳥苷三磷酸（GTP） is created from GDP by transfer of a phosphate group during the conversion of 琥珀酰輔酶A to 琥珀酸. This phosphate is transferred to ADP in another substrate-level phosphorylation event. The reaction is catalyzed by the enzyme 琥珀酰輔酶A合成酶.
Another form of Substrate-level phosphorylation is also seen in working skeletal muscles and the brain. 磷酸肌酸 is stored as a readily available high-energy phosphate supply, and the enzyme 肌酸磷酸激酶 transfers a phosphate from phosphocreatine to ADP to produce ATP. Then the ATP releases giving chemical energy.
Apart from this Substrate-level phosphorylation can also be observed in 發酵, for example, hetero乳酸發酵, butyric acid fermentation, and propanoic acid fermentation.
- 翻譯完畢——Shakiestone (留言) 2011年9月13日 (二) 13:29 (UTC)