兔肝金属硫蛋白稀水溶液γ辐解  

￣(60)Co γ-RADIOLYSIS OF DILUTED MT-I AQUEOUS SOLUTION

作　　者：方兴旺[1] 魏根栓[1] 吴季兰[1] 

机构地区：[1]北京大学技术物理系

出　　处：《辐射研究与辐射工艺学报》1994年第4期193-198,共6页Journal of Radiation Research and Radiation Processing

摘　　要：研究了氧和剂量率对免肝金属硫蛋白（ＭＴ－Ｉ）稀水溶液γ辐解的影响。水辐解产生的ＯＨ自由基主要进攻ＭＴ－Ｉ中半胱氨酸残基上的巯基，使巯基与金属离子间的配位键破坏，造成部分金属离子解高，并形成二硫键。而二硫键的形成主要发生在分子内部，其Ｇ值将为分子间二硫键Ｇ值的５倍。Ｎ２Ｏ饱和与Ｎ２饱和时ＭＴ－Ｉ稀水溶液辐解，巯基损失Ｇ值分别为７．０与４．２，Ｏ２饱和时有一较短的链反应。辐解形成的二硫键能定量地被还原型谷胱苷肽还原。同时对ＭＴ－Ｉ稀水溶液γ辐解机理进行了讨论，并求得了辐解时的物料平衡。Effects of O2 and dose rate on the radiolysis of rabbit hepatic metallothionein-I(MT-I) in phosphate buffer solution at pH 8. 0 have been studied. Active species (OH and H2O2) formed under irradiation principally attack the Zn-S bonds in the β--domain of MT-I and as a result. give birth to disulfide bonds. and the formation of disulfide bonds mainly occurs intramolecularly. The radiolysis of N2- or N2O-saturated MT-I solutions resulted in sulfhydryl-group-decrease with G-S H-=4.2and 7.2 respectively, whereas G values of dimer (G(MT-I)2) were only 0.32 and 0.67. A short chain-reaction exists in the decrease of sulfhydryl groups when O2saturated MT-I was irradiated, but it contributed little to G(MT-I)2. However, the damaged MT-I can be repaired completely by reduced glutathione. The reaction between H2O2 and MT-I also was investigated, and k2.=10mol.dm-3.s-1 for RS(MT-I) + H2O2-RSOH+ OH- was abtained. Furthermore. the radiolysis mechanism of MT-I was disscussed on the basis of above mentioned results and good material balances were achieved.

关 键 词：金属硫蛋白 Γ辐射 二硫键 辐射效应 兔肝 

分 类 号：Q51[生物学—生物化学]