钉螺酚氧化酶活性的初步研究(英文)

Preliminary study on The activity of Phenoloxidase in Oncomelania snails

目的初步探讨日本血吸虫惟一中间宿主钉螺体内酚氧化酶的生化活性。方法解剖健康成年钉螺,剔除外壳,将其分为雄性组、雌性组及雌雄混合组(雌雄重量相等),匀浆离心取上清为待检酶液。以邻苯二酚为底物通过比色法检测钉螺酚化酶在pH6.8、28℃条件下三组酶活力并予比较;用同法分别测定三组在不同pH(恒温28℃)及不同温度(pH6.8)下的酚氧化酶活力,绘制变化曲线,确定该酶活性最适pH和最适温度。通过Lineweaver-Burk双倒数作图法和Arrhenius公式求得各组酶活化能并以比较。结果在pH6.8、28℃条件下,雄性组、雌性组及混合组的酶活力分别为188.2±5.7、183.8±5.5及185.2±6.7(U/g),经方差分析,三组酶活力无显著差异。三组酚氧化酶的活性在不同pH及温度下的变化趋势无显著差异;pH为6.0、温度为40℃时,三组的酚氧化酶活性均最高。三组活化能分别为32.6±5.1、31.7±2.9及32.1±3.3(kJ/mol),经方差分析亦无显著差异。结论钉螺酚氧化酶活性及活化能均无性别差异,其催化邻苯二酚的最适pH及最适温度分别为6.0和40℃。

Objective To research biochemical activity of phenoloxidase （PO） extracted from Oncomelania snails, the unique intermediate host of Schistosoma japonicum. Methods Healthy adult Oncomelania snails were dissected and their shells were discarded. Then the snails were divided into three groups as follows： male group, female group and mixed group. PO was obtained through halogenations and centrifugation. By using colorimetric method with catechol as substrate, phenoloxidasic activity in the groups was detected under the circumstance of pH 6.8 and at the temperature of 28℃, and the results were compared .The activity was detected under the circumstances of different pH （ at the temperature of 28℃ ） and different temperatures （ at pH 6.8 ）, respectively. Then their changing tendency were drew,and the optimum pH and the optimum temperature were determined. The active energy of PO in each group was determined by the method of Lineweaver-Burk plot and Arrhenius plot. Results At pH 6.8 and temperature of 28℃, the activity of PO in the male group, the female group and the mixed group was 188.2±5.7, 183.8±5.5 and 185.2±6.7 （U/g）, respectively. It showed that there was no significant difference among the three groups by variance analysis. There was no significant difference on the changing tendency of phenoloxidasic activity in the three groups under different pH and different temperatures. The activity of the enzyme was highest at pH 6.0 and 40℃. The active energy of PO in the male group, the female group and the mixed group was 32.6±5.1, 31.7±2.9 and 32.1±3.3 （kJ/mol）, respectively. By variance analysis, it showed that there was no significant difference on the active energy among the three groups. Conclusion There is no sexually distinct difference on the activity of PO and the active energy of the enzyme in Oncomelania snails. The optimal pH and temperature that the PO in Oncomelania snails catalyzes catechol is 6.0 and 40℃, respectively.