Substrate activation of porcine pancreatic kallikrein by N alpha derivatives of arginine 4-nitroanilides.
Substrate activation of porcine pancreatic kallikrein by N alpha derivatives of arginine 4-nitroanilides.
复制标题
精氨酸 4-硝基苯胺的 N α 衍生物对猪胰激肽释放酶的底物激活。
作者：
L. Oliveira;M. S. Araujo;L. Juliano;E. Prado
研究了不同pH、温度和盐浓度条件下，猪胰激肽释放酶对几种Nα-取代的L精氨酸4-硝基苯胺的催化作用。在高底物浓度下，几乎所有底物的水解率都显着增加，偏离了Michaelis-Menten动力学。动力学数据的分析假设猪胰腺激肽释放酶存在一个与底物亲和力较低的额外结合部位。结合到这个辅助位点上会产生一种可调节的酶物种，它可以通过第二催化途径对底物的另一个分子进行水解。调节物种的米氏常数和催化速率常数均高于游离酶，提示底物激活酶的机制。动力学数据表明，在酶的主要和辅助位置的结合需要相似的底物。三(羟甲基)氨基甲烷盐酸盐和氯化钠改变了猪胰激肽释放酶对N-α-乙酰基-L-苯丙氨酸-L-精氨基-4-硝基苯胺的反应动力学参数，但不改变酶的活化模式(活化态和游离态的催化常数之比)。在不同pH和温度条件下研究D-Val-L-亮氨酸-L-Arg-4-硝基苯胺的水解性时也观察到了类似的现象。
Hydrolysis of several N alpha-substituted L-arginine 4-nitroanilides with porcine pancreatic kallikrein was studied under different conditions of pH, temperature, and salt concentration. At high substrate concentrations a deviation from Michaelis-Menten kinetics was observed with a significant increase in the hydrolysis rates of almost all substrates. Kinetic data were analyzed on the assumption that porcine pancreatic kallikrein presents an additional binding site with lower affinity for the substrate. Binding to this auxiliary site gives rise to a modulated enzyme species which can hydrolyze an additional molecule of the substrate through a second catalytic pathway. The values of both Michaelis-Menten and catalytic rate constants were higher for the modulated species than for the free enzyme, suggesting a mechanism of enzyme activation by substrate. Kinetic data indicated similar substrate requirements for binding at the primary and auxiliary sites of the enzyme. Tris(hydroxymethyl)aminomethane hydrochloride and NaCl were shown to alter the kinetic parameters of the hydrolysis of N alpha-acetyl-L-Phe-L-Arg 4-nitroanilide by porcine pancreatic kallikrein but not the enzyme activation pattern (ratio of the catalytic constants for the activated and the free enzyme forms). Similar observations were made when the hydrolysis of D-Val-L-Leu-L-Arg 4-nitroanilide was studied under different pH and temperature conditions.
影响因子：
3.9
作者：
Murthy,KK;Carretero,OA;Scicli,AG
通讯作者：
Scicli,AG
阳离子对人尿激肽释放酶活性的影响。
DOI：
--
发表时间：
1982
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Lieberthal,W;Oza,NB;Bernard,DB;Levinsky,NG
通讯作者：
Levinsky,NG
钠和其他单价阳离子对纯化激肽释放酶与膜结合激肽释放酶的抑制作用。
DOI：
--
发表时间：
1983
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Chao,J;Tanaka,S;Margolius,HS
通讯作者：
Margolius,HS