New Type 2 Copper-Cysteinate Proteins. Copper Site Histidine-to-Cysteine Mutants of Yeast Copper-Zinc Superoxide Dismutase.
New Type 2 Copper-Cysteinate Proteins. Copper Site Histidine-to-Cysteine Mutants of Yeast Copper-Zinc Superoxide Dismutase.
复制标题
新型 2 型半胱氨酸铜蛋白。
作者：
Yi Lu;J. A. Roe;C. Bender;J. Peisach;L. Banci;I. Bertini;E. B. Gralla;J. Valentine
本文报道了从酿酒酵母中制备和表征两个新的位点定向突变体铜锌超氧化物歧化酶蛋白，即His46Cys （H46C）和His120Cys (H120C)，其中铜结合位点的单个组氨酸配体被半胱氨酸取代。这两个突变CuZnSOD蛋白可以被描述为2型（或正常）而不是1型（或蓝色）铜-半胱氨酸蛋白，其特征是黄色而不是蓝色，这是由400 nm左右强烈的铜-硫电荷转移带引起的，它们的2型EPR光谱具有大而不是小的核超精细相互作用，它们的特征是2型d-d电子吸收光谱。这两个铜位点His-to-Cys突变之间的一个有趣的区别是，在H46C突变体中，两个金属位点之间的咪唑酸桥是野生型蛋白的特征，在H46C突变体中保持完整，而在H120C突变体中则不存在。
Preparation and characterization of two new site-directed mutant copper-zinc superoxide dismutase proteins from Saccharomyces cerevisiae, i.e., His46Cys (H46C) and His120Cys (H120C), in which individual histidyl ligands in the copper-binding site were replaced by cysteine, are reported here. These two mutant CuZnSOD proteins may be described as type 2 (or normal) rather than type 1 (or blue) copper-cysteinate proteins and are characterized by their yellow rather than blue color, resulting from intense copper-to-sulfur charge transfer bands around 400 nm, their type 2 EPR spectra, with large rather than small nuclear hyperfine interactions, and their characteristic type 2 d-d electronic absorption spectra. An interesting difference between these two copper site His-to-Cys mutations is that the imidazolate bridge between the two metal sites that is characteristic of the wild-type protein remains intact in the case of the H46C mutant but is not present in the case of the H120C mutant.