化学修饰单克隆抗体模拟谷胱甘肽过氧化物酶

化学修饰具有底物谷胱甘肽（ＧＳＨ）结合部位的单克隆抗体（４Ａ４），使其结合部位上的丝氨酸（Ｓｅｒ）转变成谷胱甘肽过氧化物酶（ＧＰＸ）的催化基团硒代半胱氨酸（Ｓｅ－Ｃｙｓ），因而产生高活力的含硒抗体酶（Ｓｅ－ａｂｚｙｍｅ）．突变的４Ａ４（ｍ４Ａ４）的ＧＰＸ活力达到了天然酶活力的１９％，并对ｍ４Ａ４的酶学性质和动力学性质进行了研究；硒代谷胱甘肽（ＧＳｅＨ）连到４Ａ４结合部位，其ＧＰＸ活力由３．８６Ｕ／μｍｏｌ提高到５９８．９Ｕ／μｍｏｌ用黄嘌呤氧化酶／次黄嘌呤为中心的心肌线粒体自由基损伤模型证明Ｓｅ－ａｂｚｙｍｅ（ｍ４Ａ４）可减轻活性氧对线粒体的损伤。

Imitation of GPX by Chemically Modifying Monoclonal Antibody

The Se-abzyme with Glutathione peroxidase(GPX) activity was successfully prepared by the combination of monoclonal antibody (McAb)preparation technique with simple chemical modification. That is to say , GPX catalytic group selenocysteine (SeCys) was incorporated into McAb IgG (4A4) with GSH binding site by chemical modification to generate Se-abzyme (m4A4) . The ratio in magnitude of activity of m4A4 and native GPX is 19%. Enzymatic and kinetic properties of the m4A4 were studied. γ-Glu-SeCys-Gly(GSeH) was linked into 4A4 combining site ,and the GPX activity of GSeH-4A4 was 155 times higher than that of GSeH; It was demonstrated that the m4A4 could prevent mitochondria from the free radical lesion induced by the hypoxanthine-xanthine oxidase (HX-XO)system.