Selenium Biochemistry

硒磷酸盐（SeP）是由硒磷酸合成酶（SPS）与无机形式的硒（Se）反应生成的，是合成多种硒酶所必需的高能硒化合物。纯化的酶含有结合的紫外线吸收发色团，其特征由Matt Wolfe博士描述。专门的硒递送蛋白的参与提供硒特异性SPS用于维持细胞内硒水平低于毒性水平。可以利用硒代半胱氨酸作为底物的某些类型的递送蛋白，硒代半胱氨酸裂解酶，包括来自大肠杆菌的三种NifS相关蛋白。大肠杆菌中的一种和来自范氏甲烷球菌（Methanococcus vannielii）的一种，范氏甲烷球菌是一种厌氧生物，其特别富含硒酶和硒蛋白生物合成所需的因子。 以前从M. vannielii的表达产物，并在大肠杆菌中表达。杆菌纯化兔中产生的针对分离的重组蛋白的抗体，并由Renee Pierce用于制备抗体柱。从M. vannielii和E.利用抗体柱技术有效地纯化了大肠杆菌。Kemberly Patteson对高度疏水的硒结合蛋白的物理性质进行了详细的研究，有助于解释天然和重组形式保留结合硒的能力。该蛋白质由8.8 kDa亚基组成，含有81个氨基酸，对解离具有很强的抗性，特别是通过热处理。有证据表明，存在于每个亚基中的单个半胱氨酸残基参与硒结合。一个潜在的作用的蛋白质在交付硒硒磷酸合成酶正在调查中。获得晶体形式的硒磷酸合成酶的尝试仍在继续，作为定位蛋白质上经历ATP磷酸化的位点的手段。紫外吸收发色团的身份及其作用正在继续由Matt Wolfe研究。 用~（75）Se研究了单细胞真核生物网柱藻（Dictyostellium）的硒代谢。一个突出的放射性蛋白迁移凝胶作为二聚体已部分纯化，并试图确定其身份。这种阿米巴在普通液体培养基中易于培养，使其成为研究真核生物中硒酶生物合成的有吸引力的生物体。

Selenophosphate (SeP), the energy-rich Se compound required for synthesis of many selenoenzymes is formed by selenophosphate synthetase (SPS) from ATP and an inorganic form of Se. The purified enzyme contains a bound UV absorbing chromophore characterized by Dr. Matt Wolfe. The participation of specialized selenium delivery proteins to furnish Se specifically to SPS serves to maintain intracellular levels of selenium below toxic levels. Certain classes of delivery proteins that can utilize selenocysteine as substrate, selenocysteine lyases, include three NifS related proteins from E. coli and one from Methanococcus vannielii, an anaerobic organism that is particularly rich in selenoenzymes and factors required for selenoprotein biosynthesis. A selenium-binding protein that reacts with inorganic selenium was isolated previously from M. vannielii and the gene encoding this protein was isolated, cloned, and expressed in E. coli. Antibodies produced in rabbits to the isolated recombinant protein were purified and used by Renee Pierce to prepare antibody columns. The native selenium binding protein from M. vannielii and the recombinant protein from E. coli were purified effectively using the antibody column technique. Detailed studies on the physical properties of the highly hydrophobic selenium-binding protein by Kemberly Patteson helped to explain the ability of the native and recombinant forms to retain bound selenium. The protein which consists of 8.8 kDa subunits that contain 81 amino acids is very resistant to dissociation, especially by heat treatment. There is evidence that the single cysteine residue present in each subunit participates in selenium-binding. A potential role of the protein in the delivery of selenium to selenophosphate synthetase is under investigation. Attempts to obtain selenophosphate synthetase in crystalline form are continuing as a means of locating the site on the protein that undergoes phosphorylation by ATP. The identity of the UV absorbing chromophore and its role are continuing to be investigated by Matt Wolfe. Selenium metabolism in a single celled eukaryotic organism, Dictyostellium, was investigated using 75Se by Thressa Stadtman. A prominent radioactive protein that migrated on gels as a dimer has been partially purified and attempts are under way to determine its identity. The ease of culture of this amoeba in ordinary types of liquid media make it an attractive organism for study of selenoenzyme biosynthesis in eukaryotes.