性能描述

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An essential cofactor in enzymatic acetyl transfer reactions.
Acetyl-CoA is an essential cofactor and carrier of acyl groups in enzymatic acetyl transfer reactions. It is formed either by the oxidative decarboxylation of pyruvate in mitochondria, by the oxidation of long-chain fatty acids, or by the oxidative degradation of certain amino acids. Acetyl-CoA is the starting compound for the citric acid cycle (Kreb′s cycle). It is also a key precursor in lipid biosynthesis, and the source of all fatty acid carbons. Acetyl-CoA positively regulates the activity pyruvate carboxylase. It is a precursor of the neurotransmitter acetylcholine. Histone acetylases (HAT) use Acetyl-CoA as the donor for the acetyl group use in the post-translational acetylation reactions of histone and non-histone proteins.

Biochem/physiol Actions

Acetyl-CoA is an essential cofactor and carrier of acyl groups in enzymatic acetyl transfer reactions. It is formed either by the oxidative decarboxylation of pyruvate in mitochondria, by the oxidation of long-chain fatty acids, or by the oxidative degradation of certain amino acids. Acetyl-CoA is the starting compound for the citric acid cycle (Kreb′s cycle). It is also a key precursor in lipid biosynthesis, and the source of all fatty acid carbons. Acetyl-CoA positively regulates the activity pyruvate carboxylase. It is a precursor of the neurotransmitter acetylcholine. Histone acetylases (HAT) use Acetyl-CoA as the donor for the acetyl group use in the post-translational acetylation reactions of histone and non-histone proteins.

乙酰辅酶A是辅酶A的乙酰化形式，可以看作是活化了的乙酸。 基团 (CH3CO- = 乙酰基)与辅酶A的半胱氨酸残基的SH-基团相连。这其实是高能键硫酯键。它是脂肪酸的beta-氧化及糖酵解后产生的丙酮酸氧化脱羧的产物。在许多代谢过程中起着关键的作用。

乙酰辅酶A是能源物质代谢的重要中间代谢产物，在体内能源物质代谢中是一个枢纽性的物质。糖、脂肪、蛋白质三大营养物质通过乙酰辅酶A汇聚成一条共同的代谢通路——三羧酸循环和氧化磷酸化，经过这条通路彻底氧化生成二氧化碳和水，释放能量用以ATP的合成。乙酰辅酶A是合成脂肪酸、酮体等能源物质的前体物质，也是合成胆固醇及其衍生物等生理活性物质的前体物质。

糖在体内主要的代谢途径包括： 　　
【糖的有氧氧化】葡萄糖→丙酮酸→乙酰辅酶A→CO2+H2O。此过程在只能有线粒体的细胞中进行，并且必须要有氧气供应。糖的有氧氧化是机体获得ATP的主要途径，1分子葡萄糖彻底氧化为二氧化碳和水可合成30或32分子ATP（过去的理论值为36或38分子ATP）。 　　
【糖的无氧氧化】葡萄糖→丙酮酸→乳酸。在细胞无线粒体或缺乏氧气时进行，1分子葡萄糖氧化产生2分子乳酸，净合成2分子ATP。此过程产生的乳酸如果积累过多会导致乳酸酸中毒。 　　
【糖的磷酸戊糖途径】葡萄糖→5-磷酸核糖、NADPH。此过程的产物5-磷酸核糖是合成核苷的原料之一，NADPH是细胞内良好的还原剂，为加氢反应提供氢。 　　【糖原合成】葡萄糖→肝糖原、肌糖原。糖原是机体糖的贮存形式，但由于糖原的贮存需要水的存在，因此贮存量较小，也正因为糖原亲水，所以糖原的利用速度比脂肪快。 　　
【糖转化为脂肪】葡萄糖→乙酰辅酶A→脂肪酸→脂肪。这是糖转化为脂肪的途径，脂肪是机体高度还原的能源贮存形式，疏水，可以大量贮存，但利用速度较慢。