XRAY ROTATION CAMERA STUDIES OF SULFITE OXIDASE

含铼的酶亚硫酸盐氧化酶催化 将亚硫酸盐转化为硫酸盐，这是氧化过程中的最终步骤， 半胱氨酸和蛋氨酸的降解。 缺乏这种酶， 人类通常会导致严重的神经异常， 死亡 鸡肝亚硫酸盐氧化酶与 人的酶，鸡肝酶的结构， 从SSRL收集的数据中求解到1.9 E分辨率。 的 结构表明，蛋白质是二聚体，Mo原子 五配位的三个硫配体，一个氧代基团和一个 水/羟基配体。 一个硫酸盐分子靠近钼 标识底物结合口袋。 该结构使四 与人类亚硫酸盐氧化酶缺乏症相关的变异， 与结构有关。 两个靠近硫酸盐结合位点;两个 发生在介导二聚化的结构域内。 之间的距离 32 E的血红素的Mo和Fe令人惊讶地长， 蛋白质分子内电子转移的速率。

The molybdenum-containing enzyme sulfite oxidase catalyzes the conversion of sulfite to sulfate, the terminal step in the oxidative degradation of cysteine and methionine. Deficiency of this enzyme in humans usually leads to major neurological abnormalities and early death. Chicken liver sulfite oxidase has 68% sequence identity with the human enzyme, and the structure of the chicken liver enzyme has been solved from data collected at SSRL to 1.9 E resolution. The structure reveals that the protein is dimeric, and the Mo atom pentacoordinated by three sulfur ligands, an oxo group and one water/hydroxo ligand. A sulfate molecule adjacent to the Mo identifies the substrate binding pocket. The structure enables four variants associated with sulfite oxidase deficiency in humans to be related to structure. Two are near the sulfate binding site; two occur within the domain mediating dimerization. The distance between the Mo and Fe of the heme of 32 E is surprisingly long considering the rates of intramolecular electron transfer in the protein.