Pedosphere 8(3): 251--260, 1998
ISSN 1002-0160/CN 32-1315/P
©1998 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Effects of iron and aluminum oxides and kaolinite on adsorption and activities of invertase |
| HUANG Qiao-Yun, JIANG Ming-Hua and LI Xue-Yuan |
| Department of Resources, Environment and Agrochemistry, Huazhong Agricultural University, Wuhan 430070 (China) |
| ABSTRACT |
| Experiments were conducted to study the influences of synthetic bayerite, non-crystalline aluminum oxide (N-AlOH), goethite, non-crystalline iron oxide (N-FeOH) and kaolinite on the adsorption, activity, kinetics and thermal stability of invertase. Adsorption of invertase on iron, aluminum oxides fitted Langmuir equation. The amount of invertase held on the minerals followed the sequence kaolinite > goethite > N-AlOH > bayerite > N-FeOH. No correlation was found between enzyme adsorption and the specific surface area of minerals examined. The differences in the surface structure of minerals and the arrangement of enzymatic molecules on mineral surfaces led to the different capacities of minerals for enzyme adsorption. The adsorption of invertase on bayerite, N-AlOH, goethite, N-FeOH and kaolinite was differently affected by pH. The order for the activity of invertase adsorbed on minerals was N-FeOH > N-AlOH > bayerite > reak goethite > kaolinite. The inhibition effect of minerals on enzyme activity was kaolinite > crystalline oxides > non-crystalline oxides. The pH optimum of iron oxide- and aluminum oxide-invertase complexes was similar to that of free enzyme (pH 4.0), whereas the pH optimum of kaolinite-invertase complex was one pH unit higher than that of free enzyme. The affinity to substrate and the maximum reaction velocity as well as the thermal stability of combined invertase were lower than those of the free enzyme. |
| Key Words: enzyme activity, enzyme adsorption, invertase, kaolinite, oxides |
| Citation: Huang, Q. Y., Jiang, M. H. and Li, X. Y. 1998. Effects of iron and aluminum oxides and kaolinite on adsorption and activities of invertase. Pedosphere. 8(3): 251-260. |
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