Schwabe D, Huth W
Biochim Biophys Acta. 1979 Oct 26;575(1):112-20. doi: 10.1016/0005-2760(79)90136-x.
Acetyl-CoA acetyltransferase (EC 2.3.1.9) from rat liver mitochondria, which catalyzes the first step in the biosynthesis of ketone bodies, exists in two forms, designated transferase A and transferase B. Both transferases showed immunochemical cross-reactivity, but are immunologically unrelated to cytosolic acetyl-CoA acetyltransferase activity and the mitochondrial acetyl-CoA acyltransferase from rat liver. The transferases A and B were estimated to have molecular weights of 151 000 in the absence and 40 000 in the presence of sodium dodecyl sulfate. They differ with respect to charge states and multiplicity of forms as indicated by isoelectric focusing. Transferase A appeared in two forms with isoelectric points of 8.4 and 9.1, whereas transferase B represents a stable protein state with an isoelectric point of 9.0. Kinetic analysis of the reactions leading to acetoacetyl-CoA synthesis revealed saturation curves with multiple intermediary plateaus, indicating a complex kinetic behaviour. The data presented are interpreted as representing a microheterogeneity of forms of the mitochondrial acetyl-CoA acetyltransferase. The kinetic properties exhibited suggest a role for this microheterogeneity in the regulation of ketogenesis.
大鼠肝脏线粒体中的乙酰辅酶A乙酰转移酶（EC 2.3.1.9）催化酮体生物合成的第一步，它以两种形式存在，分别称为转移酶A和转移酶B。两种转移酶均表现出免疫化学交叉反应，但在免疫上与大鼠肝脏胞质乙酰辅酶A乙酰转移酶活性以及线粒体乙酰辅酶A酰基转移酶无关。在不存在十二烷基硫酸钠的情况下，转移酶A和B的分子量估计为151000，而在存在十二烷基硫酸钠的情况下为40000。如等电聚焦所示，它们在电荷状态和形式多样性方面存在差异。转移酶A以两种形式出现，等电点分别为8.4和9.1，而转移酶B代表一种稳定的蛋白质状态，等电点为9.0。对导致乙酰乙酰辅酶A合成的反应进行动力学分析，结果显示饱和曲线具有多个中间平台，表明其动力学行为复杂。所呈现的数据被解释为代表线粒体乙酰辅酶A乙酰转移酶形式的微观异质性。所表现出的动力学特性表明这种微观异质性在酮体生成调节中起作用。
