第 24 卷第 1 期 高 校 化 学 工 程 学 报
No.1
Vol.24
2010 年 2 月 Journal of Chemical Engineering of Chinese Universities
Feb.
2010
文章编号:1003-9015(2010)01-0087-06
WRK 对枯草芽孢杆菌 NX-2 产出的 γ-谷氨酰转肽酶的不可逆抑制动力学
肖彦羚, 周 治, 姚 忠, 宋希文, 佘维娜, 刘步云, 徐 虹, 韦 萍
(南京工业大学 食品与轻工学院, 江苏 南京 210009)
摘 要:γ-谷氨酰转肽酶(GGT;EC 2.3.2.2)催化的酰基转移反应可用于制备各种具有生理活性的谷氨酰化合物,对其
开展酶活力不可逆抑制动力学研究对于阐明 GGT 的作用机制具有重要意义。今以化学抑制剂 Woodward's Reagent K
(WRK)与枯草芽孢杆菌 NX-2 产出的 GGT 进行不可逆抑制反应,根据邹氏理论测得 WRK 对 GGT 不可逆抑制反应的
微观速率常数 k
i
为 0.03015 s
1
,WRK 与酶结合常数 K
I
为 1.352 mmolL
1
。有抑制剂存在下 GGT 与供体 γ-谷氨酰对硝
基苯胺的亲和力常数 K
m
*
=3.245 mmolL
1
,GGT 酰基化最大反应速度 V
max
*
=0.3771 mmol (Ls)
1
。通过对 GGT 的失活
动力学分析得到,失活反应级数为 1.313,说明在 GGT 活性部位至少有一个谷氨酸(或天冬氨酸)残基参与催化反应。
关键词: γ-谷氨酰转肽酶;不可逆抑制;动力学;WRK
中图分类号:Q555.3 文献标识码:A
Kinetic of Irreversible Inactivation of γ-Glutamyltranspeptidase from B.subtilis NX-2
by Woodward's Reagent K
XIAO Yan-ling, ZHOU Zhi, YAO Zhong, SONG Xi-wen, SHE Wei-na,
LIU Bu-yun, XU Hong, WEI Ping
(College of Life Science and Pharmacy, Nanjing University of Technology, Nanjing 210009, China)
Abstract: γ-Glutamyltranspeptidase (GGT; EC 2.3.2.2) can catalyze the cleavage compounds and the transfer
of their γ-glutamyl groups to water or other amino acids and peptides. GGT can be used in the enzymatic
synthesis of some glutamyl compounds with special physiological activities, and its inhibition is important for
the investigation of its catalytic mechanism. The kinetic theory of the substrate reaction with irreversible
inhibition of enzyme activity proposed previously by Tsou was applied for the study of the inactivation of GGT,
and the irreversible inhibitor of Woodward’s Reagent K (WRK) was used in this study to react with GGT from
B. subtilis NX-2. As a result, the irreversible inhibition reaction rate of WRK to GGT,and the combination
constant of WRK with enzyme were determined as k
i
= 0.03015 s
1
and K
I
=1.352 mmolL
1
, respectively. When
the inhibitor presents, the Michaelis-Menten constant and the GGT maximum acylation reaction rate were found
as K
m
*
= 3.245 mmolL
1
and V
max
*
= 0.3771 mmol(Ls)
1
, respectively. Kinetic analysis reveals that the average
order of the inactivation reaction is 1.313, and it indicates that there is at least one molecule of Glu/Asp residue
exists in the active site of GGT, which plays the role of binding with the substrate during the catalytic reaction.
Key words: γ-glutamyltranspeptidase; irreversible inactivation; kinetics; WRK
1 前 言
γ-谷氨酰转肽酶(γ-glutamyltranspeptidase,GGT,EC 2.3.2.2)可特异性地将 γ-谷氨酰基转移至受体分
子,得到新的含 γ-谷氨酰基的化合物
[1]
。由于这一过程位点特异性和光学选择性强,无需对反应物进行
保护和脱保护,反应过程中也不消耗 AT P,且 GGT 来源广泛,稳定性好。因此,利用 GGT 转肽活性制
收稿日期:2009-05-06;修订日期:2009-07-24。
基金项目:国家重点基础研究发展计划资助(2009CB724706)。
作者介绍:肖彦羚(1984-),女,江苏苏州人,南京工业大学硕士生。通讯联系人:姚忠,E-mail:yaozhong@njut.edu.cn