Gawron O, Jones L
Biochim Biophys Acta. 1977 Oct 13;484(2):453-64. doi: 10.1016/0005-2744(77)90101-2.
Aconitase (citrate(isocitrate)hydro-lyase, EC 4.2.1.3) prior to activation demonstrates a single binding site for substrates and inhibitors. On the basis of kinetic experiments, at pH 8.5 and 37 degrees C, with monomeric butanedione in borate, this binding site was found to contain a single arginine residue. Dissociation constants at pH 8.5 and 37 degrees C, determined from inhibitory effects on butanedione inactivation rates are: citrate, 0.74 mM; D-isocitrate, 0.33 mM: cis-aconitate, 0.52 mM; tricarballytate, 0.42 mM; trans-aconitate, 0.025 mM. Corresponding dissociation constants for the active enzyme are: tricarballylate, 0.39 mM; trans-aconitate, 0.14 mM. Active site Fe2+ added to the enzyme on activation is therefore not required for binding. Km values are: citrate, 0.23 mM and cis-aconitate 0.012 mM. Binding to active enzyme is considered to be transition state binding.
乌头酸酶（柠檬酸（异柠檬酸）水解酶，EC 4.2.1.3）在激活之前表现出一个底物和抑制剂的单一结合位点。基于动力学实验，在pH 8.5和37℃下，在硼酸盐中使用单体丁二酮，发现该结合位点含有一个精氨酸残基。根据对丁二酮失活速率的抑制作用在pH 8.5和37℃下测定的解离常数为：柠檬酸，0.74 mM；D-异柠檬酸，0.33 mM；顺乌头酸，0.52 mM；三羧酸，0.42 mM；反乌头酸，0.025 mM。活性酶的相应解离常数为：三羧酸，0.39 mM；反乌头酸，0.14 mM。因此，激活时添加到酶上的活性位点Fe2+对于结合不是必需的。Km值为：柠檬酸，0.23 mM和顺乌头酸0.012 mM。与活性酶的结合被认为是过渡态结合。
