摘要
将丝氨酸共价偶联到兔抗人ＩｇＭ（Ｆｃμ）抗体上，以增加抗体结合部位丝氨酸残基含量．在中性条件下，丝氨酸被对苯甲基磺酰氟活化，再经ＮａＨＳｅ亲核取代，将丝氨酸诱变为硒代半胱氨酸（ＳｅＣｙｓ）．其谷胱甘肽过氧化物酶（ＧＰＸ）活性由未增加丝氨酸前的诱变抗体的７０Ｕ／μｍｏｌ提高到２１８Ｕ／μｍｏｌ，其活性为模拟物ＰＺ５１的２００多倍．
Glutathione peroxidase(GPX,EC 1.11.1.9)is a selenoenzyme.It can prevent biomembranes from oxidative damage and has potentialities to cure some diseases.The artificial imitation of GPX becomes important because of its instability and limited availability.In order to introduce selenocysteine,the catalytic group of GPX,into the binding site of antibody,serines were covalently connected to rabbit anti human IgM(Fcμ)with glutaraldehyde.The optimal amount of glutaraldehyde(1%, W/W )was found to be 50 120 μl/mg antibody.The serines in specific sites of IgM were selectively activated by phenylmethylsulfonylfluoride(PMSF)in neutral condition and substituted by sodium hydrogen selenide.The optimal amount of PMSF and NaHSe was found to be 100 mg/L and 50 mg/L,respectively.The amount of selenuim in the modified antibody was determined to be 6 8 mole per mole of antibody.The modified antibody exhibited higher GPX activity,which was 218 U/μmol,than that of unmodified antibody.The GPX activity was 3 times as great as that of the latter and 200 times more than that of PZ51.This method may be utilized to increase the GPX activities of abzymes.
出处
《中国生物化学与分子生物学报》
CAS
CSCD
1999年第3期444-447,共4页
Chinese Journal of Biochemistry and Molecular Biology
基金
国家自然科学基金
关键词
硒
模拟酶
化学修饰
抗体
GPX
Selenium,Glutathione peroxidase,Imitating enzyme,Chemical modification,Antibody
