陕西几种土壤过氧化氢酶的动力学和热力学特征

研究结果表明:供试六个土样的米氏常数,最大速度和最大速度/米氏常数,均有差异。各土壤过氧化氢酶的活化能也明显不同。活化焓差别较大,说明各土壤过氧化氢酶形成活化络合物时,底物与酶活性中心在应变和扭曲强度上的差异。活化嫡皆为负值,表明活化络合物形成时体系的有序性增加。活化自由能为正值,各土样差异较小。黄棕壤过氧化氢酶的各参数较为特殊。

THE KINETIC AND THERMODYNAMIC PROPERTIES OF CATALASES IN SEVERAL SOILS SAMPLED FROM SHAANXI PROVINCE

Six soils from Shaanxi province were sampled to study the kinetic and thermodynamic properties of catalases.The results showed that there existed certain differences in Michaell's constants, maximum velocity and Vmax/Km ratios among soils, and that the catalases activation energy in soils was distinctly different. The great discrcpeney in activation enthalpies might indic-cate that the differences were in the response to change and tension strength of the substrates and active center of catalases when active complexes were formed through soil catalases.The activation entropies being all negative might show that when the active complexes were formed, the orderliness the system increased. The results also showed that when free energy of activation was positive, the differences in various soils were small. The parameters of catalases in yellow-brown earth were more special than in other soils stud ied.