Bowien B, Mayer F, Codd G A, Schlegel H G
Arch Microbiol. 1976 Nov 2;110(23):157-66. doi: 10.1007/BF00690223.
D-Ribulose 1,5-diphosphate carboxylase has been purified from autotrophically grown cells of the facultative chemolithotrophic hydrogen bacterium Alcaligenes eutrophus. The enzyme was homogeneous by the criteria of polyacrylamide gel electrophoresis. The molecular weight of the enzyme was 505000 determined by gel filtration and sucrose density gradient centrifugation, and a sedimentation coefficient of 18.2 S was obtained. It was demonstrated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis that the enzyme consists of two types of subunits of molecular weight 52000 and 13000. Electron microscopy on the intact and the partially dissociated enzyme lead to the construction of a model for the quaternary structure of the enzyme which is composed of 8 large and 8 small subunits. The most probable symmetry of the enzyme molecule is 4:2:2. Michaelis constant (Km) values for ribulose 1,5-diphosphate, Mg2+, and CO2 were 0.59 mM, 0.33 mM, and 0.066 mM measured under air. Oxygen was a competitive inhibitor with respect to CO2 suggesting that the enzyme also exhibits an oxygenase activity. The oxygenolytic cleavage of ribulose 1,5-diphosphate was shown and a 1:1 stoichiometry between oxygen consumption and 3-phosphoglycerate formation observed.
1,5 - 二磷酸核酮糖羧化酶已从兼性化能自养氢细菌嗜糖产碱菌自养生长的细胞中纯化出来。根据聚丙烯酰胺凝胶电泳标准，该酶是均一的。通过凝胶过滤和蔗糖密度梯度离心法测定该酶的分子量为505000，沉降系数为18.2S。十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳表明该酶由分子量为52000和13000的两种亚基组成。对完整和部分解离的酶进行电子显微镜观察，构建了该酶四级结构的模型，该模型由8个大亚基和8个小亚基组成。该酶分子最可能的对称性为4:2:2。在空气中测定时，1,5 - 二磷酸核酮糖、Mg2 +和CO2的米氏常数（Km）值分别为0.59 mM、0.33 mM和0.066 mM。氧气是CO2的竞争性抑制剂，表明该酶也表现出加氧酶活性。展示了1,5 - 二磷酸核酮糖的氧解裂解，并观察到氧气消耗与3 - 磷酸甘油酸形成之间的化学计量比为1:1。
