CS acetylates OA to citrate

Mitochondrial citrate synthase (CS) dimer catalyzes the irreversible reaction of acetyl-CoA, water, and oxaloacetate to form citrate and coenzyme A. This reaction is the entry point of two-carbon units into the citric acid cycle. The reaction is subject to allosteric regulation. Most of the time, CS is trimethylated on Lys-395 which attenuates its enzymatic activity (Malecki et al. 2017). The gene encoding the human enzyme has been cloned (Goldenthal et al. 1998), but the enzyme has not been characterized in detail. Its properties are inferred from those of the well-studied homologous pig enzyme (e.g., Morgunov and Srere 1998).<br><br>CS dimer, malate dehydrogenase MDH2, and aconitase ACO2 form a multienzyme complex ("metabolon") that optimally channels the substrate flow between them (Fahien & Kmiotek, 1983; Wu & Minteer, 2014; Omini et al., 2021).

线粒体柠檬酸合成酶（CS）二聚体催化乙酰辅酶A、水与草酰乙酸不可逆反应生成柠檬酸和辅酶A。此反应为两个碳原子单元进入三羧酸循环的起始点。该反应受变构调控。大部分时间，CS在赖氨酸395位发生三甲基化，从而降低其酶活性（Malecki等，2017年）。编码人类酶的基因已被克隆（Goldenthal等，1998年），但该酶尚未进行详细表征。其性质推断自已得到充分研究的同源猪酶的性质（例如，Morgunov和Srere，1998年）。CS二聚体、苹果酸脱氢酶MDH2和柠檬酸合酶ACO2共同构成一个多酶复合体（“代谢酶复合体”），最优地调节它们之间的底物流动（Fahien & Kmiotek，1983年；Wu & Minteer，2014年；Omini等，2021年）。