Nikkola M, Gleason F K, Eklund H
Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala.
J Biol Chem. 1993 Feb 25;268(6):3845-9.
Fifteen mutant T4 glutaredoxins (previously T4 thioredoxin) have been assayed for activity with Escherichia coli thioredoxin reductase. The mutations include substitutions in the region of the active site, in the 2 cysteines, and in the 2 residues between the cysteines forming the active-site disulfide bridge. Mutant thioredoxins where substitutions have been made in charged residues around the active site show the biggest differences in activity. The positive residues Lys-13 and Lys-21 were found to be important for efficient binding to thioredoxin reductase. Substitution of the aspartic acid at position 80 with a serine produced a glutaredoxin with superior activity. This mutant glutaredoxin has earlier been shown to be more efficient than the wild type in thiol transferase activity (Nikkola, M., Gleason, F. K., Saarinen, M., Joelson, T., Björnberg, O., and Eklund, H. (1991) J. Biol. Chem. 266, 16105-16112). Even the glutaredoxin P66A, where the active-site cis-proline has been substituted, could be efficiently reduced by thioredoxin reductase. Glutaredoxins lacking one or both cysteines were not active.
已对15种突变型T4谷氧还蛋白（以前称为T4硫氧还蛋白）与大肠杆菌硫氧还蛋白还原酶的活性进行了测定。这些突变包括活性位点区域、两个半胱氨酸以及形成活性位点二硫键的两个半胱氨酸之间的两个残基的替换。在活性位点周围带电荷残基处进行替换的突变型硫氧还蛋白在活性上表现出最大差异。发现正电荷残基赖氨酸-13和赖氨酸-21对于与硫氧还蛋白还原酶的有效结合很重要。将第80位的天冬氨酸替换为丝氨酸产生了一种具有更高活性的谷氧还蛋白。这种突变型谷氧还蛋白 earlier 已被证明在硫醇转移酶活性方面比野生型更有效（Nikkola, M., Gleason, F. K., Saarinen, M., Joelson, T., Björnberg, O., and Eklund, H. (1991) J. Biol. Chem. 266, 16105 - 16112）。甚至活性位点顺式脯氨酸已被替换的谷氧还蛋白P66A也能被硫氧还蛋白还原酶有效还原。缺少一个或两个半胱氨酸的谷氧还蛋白没有活性。 （注：原文中“earlier”可能有误，推测可能是“earlier”，这里按“earlier”翻译为“更早”，但不确定是否准确）
