Characterization of Activity of a Potential Food-Grade Leucine Aminopeptidase from Kiwifruit

Abstract EN

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 Zn2+ 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.