Zhang H, Means G E
Department of Biochemistry, Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210, USA.
Anal Biochem. 1996 May 15;237(1):141-4. doi: 10.1006/abio.1996.0212.
The transfer of nitroso groups from S-nitroso-L-cysteine (1) and six other simple S-nitrosothiols to Cys 34 of bovine serum albumin (2) has been followed using Ellman's reagent, 5,5'-dithio-bis (2-nitrobenzoate) (3), to detect the resulting thiols. The described method utilizes the low reactivity of (3) with (2) and the high extinction coefficient of 2-nitro-5-thiobenzoate produced upon its reaction with thiols to follow the transfer of nitroso moieties at low concentrations where other procedures are not feasible. A second-order rate constant of 6400 M-1 s-1 obtained for the reaction of (2) with S-nitrosomercaptoethylamine is approximately 10 times faster than that for its reaction with (1), approximately 40 times faster than that for its reaction with S-nitrosoglutathione, and consistent with Cys 34 being located in a narrow crevice in close proximity to an anionic charge.
利用埃尔曼试剂5,5'-二硫代双(2-硝基苯甲酸)(3)检测生成的硫醇，研究了亚硝基从S-亚硝基-L-半胱氨酸(1)和其他六种简单的亚硝基硫醇转移至牛血清白蛋白(2)的半胱氨酸34的过程。所描述的方法利用了(3)与(2)的低反应活性以及(3)与硫醇反应生成的2-硝基-5-硫代苯甲酸的高消光系数，以便在其他方法不可行的低浓度下跟踪亚硝基部分的转移。(2)与S-亚硝基巯基乙胺反应得到的二级速率常数为6400 M-1 s-1，比其与(1)反应的速率常数快约10倍，比其与S-亚硝基谷胱甘肽反应的速率常数快约40倍，这与半胱氨酸34位于靠近阴离子电荷的狭窄缝隙中一致。
