E COLI CYSTEINE DESULFURASE (ISCS)

半胱氨酸脱硫酶催化脱除半胱氨酸中的硫 为铁硫蛋白的生物合成提供硫化物。 这种重要的酶广泛分布在原核生物和真核生物中， 此外，还发现了一种同源形式，指定为NIFS 固氮菌。在溶液中，蛋白质以二聚体形式存在。 相同的45 kDa亚基。磷酸吡哆醛(PLP)被用作一种 辅因子，但半胱氨酸脱硫酶似乎与 其他PLP酶，可能代表PLP的一个新的结构类别 酵素。我们已经克隆、高效表达和纯化了大肠杆菌 酶，命名为ISCS，并正在研究其在组装和 铁/S簇蛋白的修复。

Cysteine desulfurase catalyzes the removal of sulfur from cysteine and provides sulfide for the biosynthesis of iron-sulfur proteins. This essential enzyme is widely distributed among pro- and eukaryotes, and a homologous form, designated NifS, is additionally found in nitrogen fixing organisms. In solution the protein exists as a dimer of identical 45-kDa subunits. Pyridoxal phosphate (PLP) is used as a cofactor, but cysteine desulfurase does not appear to be homologous to other PLP enzymes and may represent a new structural class of PLP enzyme. We have cloned, overexpressed, and purified the E. coli enzyme, designated IscS, and are studying its role in assembly and repair of Fe/S cluster proteins.