胰蛋白酶与ANS的相互作用

利用荧光光谱法研究了在不同ｐＨ、压力及不同浓度的脲作用时荧光探针１，８－ＡＮＳ（１－ａｎｉｌｉｏｎｎａｐｈｔｈａｌｅｎｅ－８－ｓｕｌｆｏｎｉｃａｃｉｄ）与胰蛋白酶的相互作用．发现在低ｐＨ时ＡＮＳ可以结合到胰蛋白酶上，其中以ｐＨ２．０、３．０时结合最强．进一步的研究发现脲变性对胰蛋白酶结合ＡＮＳ的能力有很大的影响：１．５ｍｏｌ／Ｌ的脲即可使得胰蛋白酶结合ＡＮＳ的能力大大降低，但有趣的是即使高达４ｍｏｌ／Ｌ的脲对胰蛋白酶色氨酸残基荧光也无明显影响．另外，在ｐＨ猝变、脲变性、及逐渐改变压力时，胰蛋白酶色氨酸残基荧光和结合到胰蛋白酶分子上的ＡＮＳ的荧光的变化大不相同．上述结果暗示胰蛋白酶的色氨酸残基所在的区域和其结合ＡＮＳ的区域是两个不相同的区域．

The Interaction between Trypsin and Fluorescence probe ANS *

The interaction between trypsin and fluorescence probe 1,8 ANS at different pH,hydrostatic pressure and different concentration of urea was described.ANS could bind to trypsin molecule at low pH,especially at pH 2.0 and 3.0.Further study indicated that urea obviously affected ANS binding to trypsin molecule:1.5 mol/L urea greatly decreased ANS binding to trypsin molecule.However,it was interesting that no obvious change in the tryptophan fluorescence spectrum of trypsin even in 4 mol/L urea.It was found that the changes in the tryptophan fluorescence of trypsin and in the fluorescence of ANS bound to trypsin molecule were different upon the application of hydrostatic pressure,the rapid pH change and urea denaturation,implying that there exist two domains in the trypsin molecule:one is related to tryptophan residues,and the other to the ANS binding.