大肠杆菌DsbA蛋白的氧化还原性质和构象变化

DsbA蛋白是大肠杆菌周质空间内的巯基 /二硫键氧化酶 ,主要催化底物蛋白质二硫键的形成。利用定点突变结合色氨酸类似物标记技术 ,研究了DsbA蛋白的氧化还原性质和构象变化。结果显示 :(1 )DsbA蛋白的还原态比氧化态的结构更加稳定 ,说明DsbA的强氧化性来源于氧化态构象的紧张状态 ;(2 )DsbA氧化和还原态间特殊的荧光变化主要来源于Trp76在不同状态间微观环境的差异 ;(3 )色氨酸类似物标记不会对DsbA蛋白的结构和功能产生明显的影响 ,利用1 9F NMR进一步证实了DsbA氧化还原状态间的构象变化 ,而且这种变化主要影响Trp76的局部环境 ,而对Trp1 2 6的局部环境没有太大的影响

Redox Properties and Conformational Changes of DsbA protein from Escherichia coli Periplasm

DsbA protein, a disulfide bond enzyme in Escherichia coli periplasm, catalyses mainly disulfide bond formation of proteins. Site directed mutagenesis combined with Trp analog labeling technique was used to investigate the redox properties and conformational changes of DsbA. The results show that: (1) DsbA, as an oxidase, can catalyze disulfide bond formation efficiently. The reduced form is more stable than the oxidized form, suggesting that the strong oxidizing force of DsbA comes from the tense conformation of the oxidized form. (2) The alteration of local environment around Trp 76 between redox forms is responsible for the special fluorescence phenomenon of DsbA. (3) The result from 19 F NMR study provides further evidence that the local conformation of Trp 76 is dramatically affected during the transformation of redox forms, but that of Trp 126 remains unaffected.