Sugiyama S, Ohtsuki K, Sato K, Kawabata M
Department of Food Sciences and Nutritional Health, Kyoto Prefectural University, Japan.
J Nutr Sci Vitaminol (Tokyo). 1997 Oct;43(5):581-9. doi: 10.3177/jnsv.43.581.
Kiwifruit (Actinidia chinensis) contains abundant protease, actinidin, and two possible components which were named A1 and A2. However, a comparison of the two components has not been thoroughly conducted. We have previously shown the presence of six proteases named KP1, KP2, KP3, KP4, KP5 and KP6 in kiwifruit, and that each purified kiwifruit protease was chromatographically pure. It was also indicated that the two representative components, KP4 and KP6, must be A1 and A2. To establish whether or not the two proteases, KP4 and KP6, have the same specificity in proteolytic activity, their enzymatic properties were compared. Between the two proteases, differences in substrate specificity against several protein-substrates (casein, gelatin, collagen, ovalbumin and bovine serum albumin) were not observed by digestion-product analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The kinetic parameters of KP4 against N-alpha-carbobenzoxyl-lysine p-nitrophenyl esters were different from those of KP6. The pH-activity profiles of KP4 and KP6 against S-3-trimethylaminopropyl-lysozyme, a wide-pH range soluble substrate, and N-alpha-carbobenzoxyl-lysine p-nitrophenyl esters were different.
猕猴桃（中华猕猴桃）含有丰富的蛋白酶、猕猴桃蛋白酶以及两种可能的成分，分别命名为A1和A2。然而，尚未对这两种成分进行全面比较。我们之前已表明猕猴桃中存在六种蛋白酶，分别命名为KP1、KP2、KP3、KP4、KP5和KP6，并且每种纯化的猕猴桃蛋白酶在色谱上都是纯的。还表明两种代表性成分KP4和KP6必定是A1和A2。为确定这两种蛋白酶KP4和KP6在蛋白水解活性方面是否具有相同的特异性，对它们的酶学性质进行了比较。通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳进行消化产物分析，未观察到这两种蛋白酶对几种蛋白质底物（酪蛋白、明胶、胶原蛋白、卵清蛋白和牛血清白蛋白）的底物特异性存在差异。KP4对N-α-苄氧羰基 - 赖氨酸对硝基苯酯的动力学参数与KP6不同。KP4和KP6对S-3-三甲基氨基丙基溶菌酶（一种在宽pH范围内可溶的底物）和N-α-苄氧羰基 - 赖氨酸对硝基苯酯的pH-活性曲线不同。
