Studies on Protease of the Rotifer, Brachionus plicatilis―II Hydrolytic Properties on Some Synthetic Substrates

摘要

Some properties of acid and alkaline proteinase activities in crude extract from the rotifer, Brachionus plicatilis, were reported in the previous paper (1). In the present paper, some properties of hydrolytic activities by the enzyme on CGT, BAA and GPA were investigated. The results of this study were summarized as follows. 1) Two kinds of CGT hydrolytic activity were detected, one was acting in acid pH range (optimum pH was 2.0) and the other was in neutral range (optimum pH was 7.5). The enzyme activity in acid pH range was very unstable and disappeared completely as exposed to room temperature at pH 2.0 for 4 hours. The enzyme activity at pH 7.5 was activated by means of preincubation at 50°～60℃ for 30 minutes, and inhibited with IAA. 2) The optimum pH for BAA hydrolytic activity was about 6 and cysteine was required to activate the enzyme, which was inhibited considerably with Zn²⁺ and IAA, and partially with I₂ and PCMB. 3) GPA hydrolytic activity required cysteine too. The optimum pH was about 6 and the activity was inhibited with Zn²⁺, I₂ and PCMB.