Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, 40002, Thailand.
Sci Rep. 2021 Mar 11;11(1):5727. doi: 10.1038/s41598-021-85258-7.
This study investigated the biochemical properties, enzyme activities, isoenzyme pattern, and molecular weight of three types of digestive enzyme from six freshwater fish species: Puntius gonionotus (common silver barb), Puntioplites proctozysron (Smith's barb), Oreochromis niloticus (Nile tilapia), Hemibagrus spilopterus (yellow mystus), Ompok bimaculatus (butter catfish), and Kryptopterus geminus (sheatfish). The optimum pHs for amylase and alkaline protease activities were 7.0-8.0 and 8.0-10.0, and the optimum temperatures were 45-60 °C and 50-55 °C, respectively. A pepsin-like enzyme was detected in all three carnivorous fishes (Ompok bimaculatus, Kryptopterus geminus, and Hemibagrus spilopterus) with optimum reaction pH of 2.0 for each and optimum reaction temperatures 50-55 °C. In optimum reaction conditions, the amylase and alkaline protease from Puntioplites proctozyron showed the highest activities. Lower activities of all enzymes were observed at temperature (29 °C) of Lam Nam Choen swamp than at the optimum reaction temperatures. The fish species contained one to three and five to eight isoforms of amylase and alkaline protease, respectively, with molecular weights from 19.5 to 175 kDa. Both the alkaline proteases and amylases were stable in wide pH and temperature ranges.
本研究调查了 6 种淡水鱼类（Puntius gonionotus（普通银鲃）、Puntioplites proctozysron（Smith's 鲃）、Oreochromis niloticus（尼罗罗非鱼）、Hemibagrus spilopterus（黄颡鱼）、Ompok bimaculatus（鲇）和 Kryptopterus geminus（鳝））的 3 种消化酶的生化特性、酶活性、同工酶模式和分子量。淀粉酶和碱性蛋白酶的最适 pH 值分别为 7.0-8.0 和 8.0-10.0，最适温度分别为 45-60°C 和 50-55°C。在所有三种肉食性鱼类（Ompok bimaculatus、Kryptopterus geminus 和 Hemibagrus spilopterus）中都检测到一种类似于胃蛋白酶的酶，最适反应 pH 值为 2.0，最适反应温度为 50-55°C。在最适反应条件下，Puntioplites proctozyron 的淀粉酶和碱性蛋白酶表现出最高的活性。在 Lam Nam Choen 沼泽的温度（29°C）下，所有酶的活性均低于最适反应温度。鱼体内含有 1 到 3 种和 5 到 8 种同工型的淀粉酶和碱性蛋白酶，分子量从 19.5 到 175 kDa 不等。碱性蛋白酶和淀粉酶在较宽的 pH 和温度范围内都很稳定。
