Alberts A W, Gordon S G, Vagelos P R
Proc Natl Acad Sci U S A. 1971 Jun;68(6):1259-63. doi: 10.1073/pnas.68.6.1259.
Acetyl CoA carboxylase of Escherichia coli has been resolved into three functionally dissimilar proteins: (1) biotin-carboxyl carrier protein (BCCP); (2) a biotin carboxylase component that catalyzes the Mn-ATP-dependent carboxylation of BCCP to form CO(2) (-)-BCCP; and (3) a transcarboxylase component that catalyzes the transfer of the carboxyl group from CO(2) (-)-BCCP to acetyl CoA to form malonyl CoA.The transcarboxylase has been purified 1700-fold. Evidence that this protein catalyzes the transcarboxylase step includes the demonstration that it (a) catalyzes the carboxylation of BCCP, (b) catalyzes the BCCP-dependent exchange between [(14)C]acetyl CoA and malonyl CoA, (c) binds labeled acetyl CoA and malonyl CoA, and (d) catalyzes the decarboxylation of CO(2) (-)-BCCP. On the basis of this evidence, it is concluded that the transcarboxylase component contains sites for the acyl CoA group and for biotin, the covalently bound prosthetic group of BCCP.
大肠杆菌的乙酰辅酶A羧化酶已被分解为三种功能不同的蛋白质：（1）生物素羧基载体蛋白（BCCP）；（2）一种生物素羧化酶成分，催化BCCP的锰-ATP依赖性羧化反应，形成CO₂⁻-BCCP；（3）一种转羧酶成分，催化羧基从CO₂⁻-BCCP转移到乙酰辅酶A，形成丙二酸单酰辅酶A。转羧酶已被纯化了1700倍。该蛋白质催化转羧酶步骤的证据包括：证明它（a）催化BCCP的羧化反应，（b）催化[(¹⁴)C]乙酰辅酶A和丙二酸单酰辅酶A之间依赖于BCCP的交换反应，（c）结合标记的乙酰辅酶A和丙二酸单酰辅酶A，以及（d）催化CO₂⁻-BCCP的脱羧反应。基于这些证据，可以得出结论：转羧酶成分包含酰基辅酶A基团和生物素的结合位点，生物素是BCCP的共价结合辅基。
