作　　者： ; ; ; ;

机构地区： 北京大学化学与分子工程学院化学生物学系

出　　处： 《生物化学与生物物理学报》 1994年第1期87-94,共8页

摘　　要： 用圆二色谱研究兔肝脱金属硫蛋白的两个亚型ａｐｏ－ＭＴ１、ａｐｏ－ＭＴ２与Ｈｇ２＋在不同分子数比和ｐＨ值下的络合规律。发现：（１）在ｐＨ２下与Ｈｇ２＋重组ＭＴｓ的ＣＤ谱特征峰是３０４ｎｍ（＋）、２６０ｎｍ（一）、２５０ｎｍ（＋）。络合Ｈｇ２＋的数目ｎ远远超过７。任何ｐＨ值下过量Ｈｇ２＋的存在都将破坏ＭＴｓ的正常构象。ｐＨ值对形成和维持ＭＴｓ稳定构象的影响很大，当ｐＨ≥４．９时，ａｐｏ－ＭＴｓ与Ｈｇ２＋不能重组为具有正常构象的ＭＴｓ。（２）ａｐｅ－ＭＴ１和ａｐｏ－ＭＴ２与汞作用的规律不同。ａｐｏ－ＭＴ１络合的Ｈｇ２＋离子数比ａｐｏ－ＭＴ２更多，其分子构象对ｐＨ变化的适应能力和稳定性更强。本文结果有助于理解ＭＴ的生物功能和对汞的解毒机理。 Oircular dichroism was used to study the study the behaviour of rabbit liver apo-MTT.and apo-MT2 bonding Hg2+ ions at various Hg2+ to apo-MTs molecular ratios and different pH Values. It Was found that (1) at pH2 the characteristic OD bands are shown at 304 nm(+), 260nm(-), 250 nm(+). The number of bonded Hg2+ ions per MT molecule is far greater than 7. The normal MT conformation is broken in the Presence of excess Hg2+ at any pH value. The pH dependency of making MTs and remaining stable MTs conformation is sensitive while pH≥4.9 apo-MTs can not be reconstituted with Hg2+ to form MTs which have the normal conformation.(2)apo-MT1 and apo-MT2 are different: The unmber of Hg2+ ions bonded with apo-MT1 is greater than that with apo-MT2 and the conformation of the former is more atable with varying pH values. Our present results do help us to understand the biologieal functions of MTs and the mechanism of their antitoxic effect against mercury.

关 键 词： 金属硫蛋白 汞 络合作用 构象

领　　域： [生物学]