大豆胰蛋白酶抑制剂对南极磷虾类胰蛋白酶的抑制动力学

为了探讨大豆胰蛋白酶抑制剂(STI)对南极磷虾(Euphausia superba)类胰蛋白酶的抑制动力学,采用邹氏不可逆抑制动力学法,测定了STI对该酶的微观速度常数。结果表明:南极磷虾类胰蛋白酶的Km和Vmax分别为0.155 mmol/L,8.44μmol/(L.min)。酶活力随着STI溶液浓度增大而减小,其IC50约为2.8μg/mL;低浓度的STI溶液对酶的抑制作用为竞争性慢可逆抑制。正向微观速度常数k+0为0.184 mmol/(L.min),逆向微观速度常数k-0为0.039 4 min-1,随着STI溶液浓度的逐渐增大,该酶最终将完全失活。本研究旨为该酶的抑制技术研究提供实验数据。

Kinetics of inhibition of trypsin-like enzyme from Euphausia superba by STI

To study the kinetics of inhibition of trypsin-like protease from Euphausia superba by soybean trypsin inhibitor(STI),the kinetic theory by Tsou of irreversible inactivation was applied to measure its microscopic rate constants.The values of Km and Vmax were 0.155 mmol/L and 8.44 μmol/(L·min),respectively.As the concentra-tion of STI was increased,the activity decreased with IC50 of 2.8 μg/mL.STI slowly,reversibly and competitively inhibited the enzyme activity at low concentration.The rate constant of the forward inactivation(k+0) was 0.184 min-1,which was about five times higher than the value of 0.039 4 min-1 for the reverse reactivation(k-0).There-fore,at sufficiently high STI concentrations,the enzyme would be completely inactivated.This study provides experimental data for further research into the inhibition technology of the trypsin-like protease from E.superba.