无花果蛋白酶催化的反应。α-N-苯甲酰-L-精氨酸乙酯和α-N-苯甲酰-L-精氨酰胺的水解反应。
Ficin-Catalyzed Reactions. Hydrolysis of alpha-N-Benzoyl-l-Arginine Ethyl Ester and alpha-N-Benzoyl-l-Argininamide.
作者信息
Kramer D E, Whitaker J R
机构信息
Department of Food Science and Technology, University of California, Davis, California 95616.
出版信息
Plant Physiol. 1969 Apr;44(4):609-14. doi: 10.1104/pp.44.4.609.
The effect of pH on the hydrolysis of alpha-N-benzoyl-l-arginine ethyl ester (BAEE) and alpha-N-benzoyl-l-argininamide (BAA) by a proteolytic enzyme component purified from Ficus carica var. Kadota latex has been studied in detail over the pH range of 3 to 9.5. k(cat) (lim) values for the hydrolysis of BAEE and BAA were essentially identical (5.20 and 5.01 sec(-1), respectively at 30 degrees ). k(cat) values for hydrolysis of BAEE and BAA were dependent on prototropic groups with apparent pK values of 4.24 and 8.53 and 4.10 and 8.59, respectively. k(cat) (lim) values for tht hydrolysis of BAEE and BAA were essentially identical (5.20 and groups of pK 4.33 and 8.60 and 4.55 and 8.51, respectively. Thus the pH optimum is 6.5 for both substrates. K(m) (app) values for BAEE and BAA were 3.32 x 10(-2)m and 6.03 x 10(-2)m respectively over the pH range of 3.9 to 8.0. These data are interpreted in terms of the involvement of a carboxyl and a sulfhydryl group in the active center of the enzyme. The data do not support the concept that deacylation of the acyl-enzyme is completely the rate controlling step in the hydrolyses. Rather, it appears that the magnitude of k(2) and k(3) are not greatly different.
已对从卡多塔无花果乳胶中纯化得到的一种蛋白水解酶成分在pH值3至9.5范围内对α-N-苯甲酰-L-精氨酸乙酯（BAEE）和α-N-苯甲酰-L-精氨酰胺（BAA）水解的影响进行了详细研究。在30摄氏度时，BAEE和BAA水解的k(cat)(lim)值基本相同（分别为5.20和5.01秒^(-1)）。BAEE和BAA水解的k(cat)值取决于质子转移基团，其表观pK值分别为4.24和8.53以及4.10和8.59。BAEE和BAA水解的k(cat)(lim)值基本相同（分别为5.20以及pK为4.33和8.60以及4.55和8.51的基团）。因此，两种底物的最适pH均为6.5。在pH值3.9至8.0范围内，BAEE和BAA的K(m)(app)值分别为3.32×10^(-2)m和6.03×10^(-2)m。这些数据表明酶活性中心涉及一个羧基和一个巯基。这些数据不支持酰基酶脱酰化是水解中完全的速率控制步骤这一概念。相反，似乎k(2)和k(3)的大小差异不大。
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