摘要
在胰蛋白酶介质中加入Pb2+,研究其对胰蛋白酶活性影响的作用机理。结果表明低浓度的Pb2+对酶有激活作用,高浓度则严重抑制酶活性。在高浓度下,Pb2+能完全竞争出胰蛋白酶中的Ca2+而结合到了胰蛋白酶上,其EXAFS的测试表明Pb2+与多肽链氨基酸残基上的氨基或羧基发生了配位,配位数为2,Pb-N或Pb-O键长为0.241nm。圆二色谱测试表明高浓度的Pb2+结合使胰蛋白酶的二级结构被破坏,α-螺旋含量、β-转角及无规则卷曲下降,β-折叠增加,因而使酶失去活性。
The activity of trypsin from bovine pancreas was enhanced under the treatment by Ph2+ at low concentration (0.5 similar to 3 mumol (.) L-1) but was inhibited by Pb2+ at high concentration (3 mumol (.) L-1 above). Pb2+ at high concentration could competitively displace Ca2+ from trypsin. The EXAFS demonstrated that Pb2+ bound to polypeptide chain of trypsin, coordination atom was nitrogen or oxygen, its coordination number was 2 and Pb-N (or 0) bond length was 0.241 nm. The secondary structure of trypsin was greatly changed by Pb2+ at high concentration, e. g. a-helix, beta-turn and Random coil contents decreased and beta-sheet increased. It suggested that Pb2+ bound result in trypsin conformational changed, and enzyme activity decreased.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2003年第2期129-132,共4页
Chinese Journal of Inorganic Chemistry
基金
苏州大学人才引进基金资助项目(No.Q3114102)
