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INFLUENCES OF SEVERAL SOIL COLLOIDS ON THE adsorption AND PROPERTIES OF UREASE enzyme

Journal of Wuhan University of Technology(Materials Science) 1997年第Z1期12卷 25-32页

作者：黄巧云 Huazhong Agricultural University

The present experiment was designed to elucidate the effects of the sterilized colloids separated from red soil,latosol and yellow brown soil,which are the typical zonal soils in central-south China, on the adsorption,activity,kinetic parameters and thermal stability of urease enzyme which plays significant role in the transformation of soil nitrogen compounds. Results show that the amount of enzyme adsorbed on the examined soil colloids followed the order: yellow brown soil>red soil=latosol. The residual activities of enzyme in different colloid systems are in the following sequence:red soil>latosol> yellow brown soil. The thermal stability of adsorbed enzyme is higher than that of free enzyme. The enzyme immobilized on yellow brown soil colloid had the highest stability at elevated temperature from 60 to 80℃. Both of the free and immobilized urease obey Michaelis-Menten kinetics. The Km values of immobilized urease (13. 5-20. 8 mM) on different soil colloids examined were in the same order of magnitude as that of free urease (9. 3mM). The kinetic constant of immobilized enzyme suggests that urease adsorbed on yellow brown soil colloid has a greater affinity for substrate. The Ku and Vmax values also indicate a mixed type of enzyme inhibition for the examined soil colloids. These results provide basic evidences for the understanding of the properties and kinetics of soil enzymes in tropic and subtropic regions.

关键词： urease enzyme activity enzyme adsorption soil colloid

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Investigation of the Interaction Mechanism between Lignin Structural Units and enzyme

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Journal of Renewable Materials 2023年第4期11卷 1613-1626页

作者： Lijing Huang Penghui Li Kangjie Jiang Wenjuan Wu Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources Nanjing Forestry UniversityNanjing210037China

The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with *** wood lignin(MWL)was isolated from different hardwoods of poplar,eucalyptus and *** isolated lignin samples were characterized by elemental analysis,gel permeation chromatography,nitrobenzene oxidation and fourier infrared *** mechanism of lignin structural units on enzymatic hydrolysis of cellulose was studied by quartz crystal microbalance(QCM).The results showed that different structural units of lignin had different adsorption capacity for *** results of nitrobenzene oxidation indicated that the S/G ratio(S:syringyl-like lignin structures;G:guaiacyl-like lignin structures)of lignin of poplar was 0.99,that of eucalyptus was 1.92 and that of acacia was *** to the results of QCM,the adsorption capacity of the three lignin films was as follows:Poplar MWL(S/G ratio 0.99)enzymes and more non-productive adsorption with enzymes,resulting in less adsorption between enzymes and cellulose,and lower enzymatic hydrolysis efficiency.

关键词： Lignin structural unit enzyme adsorption enzymatic hydrolysis

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Short-term effects of maize residue biochar on kinetic and thermodynamic parameters of soil β-glucosidase

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Biochar 2019年第2期1卷 213-227页

作者： Fayez Raiesi Allahyar Khadem Department of Soil Science and Engineering Faculty of AgricultureShahrekord UniversityP.O.Box 115ShahrekordIran

Soil β-glucosidase (BG), the rate-limiting enzyme in the final step of cellulose hydrolysis, plays a key role in microbial metabolism, carbon (C) cycling and sequestration in terrestrial ecosystems. Biochar application is known to affect soil BG activity;however, most of the biochar studies have focused on the potential activity of BG, and it is not clear how biochar influences the kinetic and thermodynamic behavior of BG in the soil. The objective of this study was to investigate the effect of maize residue biochar on soil BG kinetic and thermodynamic parameters. Soil BG kinetic (V_(max) and K_(m)) and ther-modynamic (E_(a), ΔH_(a) and Q_(10)) parameters were determined within soils (clayey and sandy loam soils) amended with either maize residue (as positive control) or its biochar (600℃) at 0.5 and 1.0% ratios (w/w), and the mixtures were incubated for 90 days. BG showed an increase in potential enzymatic activity (81%), enzyme concentration (higher V_(max) value) (25%) and substrate affinity (lower K_(m) value) (32%) in the biochar-amended sandy loam soil only at high addition rates compared with the control, and an increase by about 86% of the catalytic efficiency (V_(max)/K_(m)). In the clayey soil, biochar addition decreased potential BG activity (by 10-29%), increased the V_(max) value (by 20-25%) and had no impact on enzyme-substrate binding affinity, but still increased the catalytic efficiency by 47-72%. adsorption of soil BG by biochar particles did not affect the catalytic efficiency in the soil. Generally, application of maize residue biochar to the soil decreased the E_(a), ΔH_(a) and Q_(10) values of BG compared with the negative controls at both biochar rates in the light-textured soil and only at low biochar rate in heavy-textured soil. The direction and magnitude of BG responses (activity, kinetics, and thermodynamics) to biochar were more related to the soil characteristics. Biochar would increase soil BG thermal stability and decrease its sensiti

关键词： Biochar β-Glucosidase behavior Thermal sensitivity enzyme adsorption Soil texture C cycle

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Effects of Iron and Aluminum Oxides and Kaolinite on adsorption and Activities of Invertase *1

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Pedosphere 1998年第3期8卷 251-260页

作者： HUANGQIAOYUN JIANGMINGHUA 等 DepartmentofResources EnvironmentandAgrochemistryHuazhongAgricultualUniversiyWuhan430070（China） Dep

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 inv ertase 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.

关键词： enzyme activity enzyme adsorption invertase kaolinite oxides

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