食品科学 ›› 2005, Vol. 26 ›› Issue (3): 46-49.

• 基础研究 • 上一篇    下一篇

两种大豆胰蛋白酶抑制剂的抑制活性及二级结构分析比较

 黄惠华, 粱汉华, 郭乾初   

  1. 华南理工大学食品工程系; 香港理工大学应用化学与生物技术系
  • 出版日期:2005-03-15 发布日期:2011-09-19

Inhibitory Activities and Secondary Structures of Two Types of Soybean Trypsin Inhibitors

 HUANG  Hui-Hua, LIANG  Han-Hua, GUO  Qian-Chu   

  1. 1.Department of Food Engineering, South China University of Technology; 2.Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University
  • Online:2005-03-15 Published:2011-09-19

摘要: 研究了I型Kunitz大豆胰蛋白酶抑制剂(I-KSTI)和Bowman-Birk大豆胰蛋白酶抑制剂(BBTI)对胰蛋白酶的抑制活性及其二级结构的组成差异。发现I-KSTI及 BBTI对胰蛋白酶的抑制曲线分为两部分:活性急剧下降部分和缓慢下降部分。使胰蛋白酶的活性降为原来的一半时的I-KSTI和BBTI浓度为1.5μg/ml 和1.2μg/ml。使胰蛋白酶活性趋向于零(完全钝化)时的I-KSTI浓度为13.5μg/ml,而BBTI则为9μg/ml。两种抑制剂的存在不改变胰蛋白酶的Km值,但其Vmax随抑制剂浓度的增加而下降。表明其对胰蛋白酶的抑制作用是一种非竞争性抑制作用。远紫外圆二色谱的研究发现I-KSTI和BBTI的单一吸收负峰在200nm波长处,I-KSTI的克分子椭圆度[θ]200nm=-2545deg·cm2/d mol,其二级结构由22.5%β折叠,16.25%β转角和61.4%无规卷曲组成;BBTI的[θ]200nm=-797deg·cm2/d mol,由52.6%β折叠和47.4%无规卷曲组成。

关键词: 大豆胰蛋白酶抑制剂, 圆二色谱, 二级结构

Abstract: The inhibition curves of I-KSTI and BBTI against trypsin showed that the concentrations to attain 50% inhibitory ratio of trypsin activity were about 1.5μg/ml and 1.2μg/ml for I-KSTI and BBTI respectively. Complete inhibition concentrations against trypsin for BBTI and I-KSTI were 13.5μg/ml, 9μg/ml。In the presence of I-KSTI and BBTI, the Km value of trypsin was kept unchanged at 5.88×10-4 mol/L for benzoyl-DL Arginine-p-nitroanilide substrate while the Vmax was decreased. The far-UV CD (circular dichroism) spectra of both I-SKTI and BBTI showed a single negative peak at around 200nm and the negative minimum was measured as [θ]200nm=-2545deg.cm2/dmol for I-SKTI and [θ]200nm=-797deg.cm2/dmol for BBTI. The secondary structure of I-KSTI was composed of β-sheet (22.5%), β-turn (16.2%) and random (61.4%) whereas BBTI was composed only of β-sheet (52.6%) and random (47.4%).

Key words: soybean trypsin inhibitors, circular dichroism, secondary structure