摘要
本文研究了几种金属离子对锯缘青蟹(Scylla serrata)N-乙酰-β-D-氨基葡萄糖苷酶(NAGase)活力的影响.其结果表明:Li+、Na+和K+对酶活力没有明显影响,Mg2+、Ca2+和Ba2+对该酶均有激活作用,激活程度依次为Ca2+>Ba2+>Mg2+.A l3+、Fe3+、Cd2+、Pb2+和Hg2+对该酶具有一定的抑制作用,2.0μmol/dm3的Hg2+可以使酶活力完全丧失.Co2+对酶的效应是先激活后抑制,Mn2+对酶仅有轻微的激活作用.Cd2+和Fe3+对锯缘青蟹NAGase的抑制作用都呈竞争性-反竞争性混合Ⅱ型效应,Cd2+的抑制常数KI和KIS分别为23.9、5.0 mmol/dm3,Fe3+的抑制常数KI和KIS分别为395.5、135.6μmol/dm3.KI>KIS,说明酶-底物络合物(ES)与抑制剂的亲和力比游离酶(E)与抑制剂的亲和力大.
The effects of some metal ions on the activity of N-acetyl-β-D-glucosaminidase （NAGase） from green crab （Scylla serrata） have been studied and the results show that Li^＋ , Na^＋ and K^＋ have no effect on the enzyme activity; Mg^2＋ , Ca^2＋ and Ba^2＋ activate the enzyme with an order of Ca^2＋ 〉 Ba^2＋ 〉 Mg^2＋ in intensity, while Al^3＋ , Fe^3＋ , Cd^2＋ , Pb^2＋ and Hg^2＋ inhibit the enzyme activity. 2. 0μmol/dm^3 of Hg^2＋ decreases the enzyme activity completely. Co^2＋ activates the enzyme at concentration lower than 4. 0 mmol/dm^3 but inhibits it at higher concentration. Mn^2＋ has a little active effects on the enzyme. Inhibitory kinetics of Cd^2＋ and Fe^3＋ on the enzyme has beea studied. It shows that the inhibition type of Cd^2＋ and Fe^3＋on the enzyme is of mix-typed Ⅱ. The combination constants of Cd^2＋ and Fe^3＋ with free enzyme （ KI） and enzyme-substrate complex （ KIS ） were determined respectively. The values of KI and KIS are abtained as 23.9 and 5. Ommol/dm^3 for Cd^2＋ and 395.5 and 135.6μmol/dm^3 for Fe^3＋ , respectively. K, is larger than K,s, which elucidates that Cd^2＋ and Fe^3＋ inhibit enzyme-substrate complex much potently than free enzyme.
出处
《台湾海峡》
CAS
CSCD
北大核心
2006年第3期343-347,共5页
Journal of Oceanography In Taiwan Strait
基金
国家自然科学基金资助项目(40576066)
厦门大学细胞生物学与肿瘤细胞工程教育部重点实验室开放基金资助项目(2005101)
