酒石酸对黏粒矿物上酸性磷酸酶吸附及活性的影响

EFFECT OF TARTRATE ON ADSORPTION AND ACTIVITY OF ACID PHOSPHATASE BY SELECTED SOIL COLLOIDS AND MINERALS

采用平衡批处理法，研究了模拟根系分泌物——酒石酸溶液的浓度（0～80mmol L^-1）、pH（2．5～7．0）对酸性磷酸酶在针铁矿、高岭石及黄棕壤和砖红壤胶体（〈2μm）上的吸附及比活性影响。结果表明，当酒石酸浓度由0mmolL^-1（作为对照）升高至80mmolL^-1时，酸性磷酸酶在供试土壤胶体和矿物表面的吸附量先急剧降低（0～5mmolL^-1之间），后逐渐达到平衡；以羟基化表面为主的针铁矿对酸性磷酸酶的吸附百分率受酒石酸浓度的影响最大，吸附百分率从对照的96．2％降至80mmolL^-1酒石酸浓度时的33．7％，其他以层状铝硅酸盐矿物为主的供试土壤胶体和高岭石则受影响较小，吸附百分率从对照的76．3％～60．6％降至80mmolL^-1酒石酸浓度时的56．2％～41．6％。酸性磷酸酶在酒石酸体系中的最大吸附pH点均在该酶的等电点酸侧，这可能与酒石酸对矿物表面的电荷性质改变有关；酒石酸体系中，针铁矿上酸性磷酸酶的比活性远高于其它供试土壤胶体，该酶的最适比活性点随胶体类型的不同而无变化或有所高移。

Effects of concentration（0 - 80 mmol L^-1）and pH（2.5 - 7.0） of the solution of tartrate, a simulative rhizospheric exudate on adsorption and specific activity of acid phosphatase on goethite, kaolinite, and colloids in yellow brown soil and latosol were studied. Results suggest that the adsorption of enzyme on soil colloids and minerals exhibited a sharp downfall （0 - 5 mmol L^- 1 ）, which was soon leveled off with rising tartrate concentration from 0 to 80 mmol L^- 1. The effect of tartrate concentration on enzyme adsorption was the most remarkable （the adsorption percentage reduced from 96.2 % in referenced system to 33.7% in 80 mmol L^- 1 tartrate system） on goethite,but much lower （the adsorption percentage reduced from 76.3% - 60.6% to 56.2 % -41.6 % in 80 mmol L^-1 tartrate system） on soil colloids composed of phyllo-aluminosilicate mineral and kaolinite. The pH value triggering the maximum adsorption of enzyme was on the acid side of the IEP of the enzyme, which may probably be related to the change induced by tartrate in electric charge property of the minerals. In the tartrate system, specific activity of the enzyme was much higher on goethite than on the colloids. The most proper specific activity point of the enzyme did not vary much with the type of colloid.