Premarathne A A A, Leung David W M
School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
Enzyme Res. 2010 Nov 4;2010:517283. doi: 10.4061/2010/517283.
Aminopeptidase (AP) activity in ripe but firm fruit of Actinidia deliciosa was characterized using L-leucine-p-nitroanilide as a substrate. The enzyme activity was the highest under alkaline conditions and was thermolabile. EDTA, 1,10-phenanthroline, iodoacetamide, and Zn(2+) had inhibitory effect while a low concentration of dithiothreitol (DTT) had stimulatory effect on kiwifruit AP activity. However, DTT was not essential for the enzyme activity. The results obtained indicated that the kiwifruit AP was a thiol-dependent metalloprotease. Its activity was the highest in the seeds, followed by the core and pericarp tissues of the fruit. The elution profile of the AP activity from a DEAE-cellulose column suggested that there were at least two AP isozymes in kiwifruit: one unadsorbed and one adsorbed fractions. It is concluded that useful food-grade aminopeptidases from kiwifruit could be revealed using more specific substrates.
以L-亮氨酸-对硝基苯胺为底物，对美味猕猴桃成熟但硬实果实中的氨肽酶（AP）活性进行了表征。该酶活性在碱性条件下最高，且不耐热。EDTA、1,10-菲啰啉、碘乙酰胺和Zn(2+)具有抑制作用，而低浓度的二硫苏糖醇（DTT）对猕猴桃AP活性有刺激作用。然而，DTT对酶活性并非必不可少。所得结果表明，猕猴桃AP是一种硫醇依赖性金属蛋白酶。其活性在种子中最高，其次是果实的果心和果皮组织。从DEAE-纤维素柱上洗脱AP活性的图谱表明，猕猴桃中至少有两种AP同工酶：一种未吸附部分和一种吸附部分。得出的结论是，使用更具特异性的底物可以揭示猕猴桃中有用的食品级氨肽酶。
