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Enhancing thermostability of -mannanase by protective additives

LIU Zhaohui, QI Wei, WU Weina, LIU Yue, HE Zhimin

《化学科学与工程前沿（英文）》 2008年第2卷第4期页码 439-442 doi: 10.1007/s11705-008-0062-8

摘要： The effects of some sugars (glucose, mannose, fructose, sucrose and chitosan) and polyols (glycol, glycerol and sorbitol) as protective additive on the thermostability of -mannanase were studied. The optimal reaction temperatures of -mannanase and the thermodynamics and the deactivation kinetics with or without additives were also investigated. The experimental results show that sucrose, chitosan and sorbitol could apparently improve the thermal stability of -mannanase when their concentration was kept at 2 g/L. The optimal combination additive proportion was sucrose: chitosan : sorbitol = 1 : 2 : 2 (molar ratio) using the orthogonal experimental design. The sucrose, chitosan, glycerol, sorbitol and the combination additive might increase the optimal reaction temperature from 50°C to about 60°C due to their good protection effect. The thermal deactivation curves of -mannanase accorded with the kinetic rules of first order reaction, and the corresponding kinetic and thermodynamic parameters were calculated. Meanwhile, the protective mechanism of the additives against deactivation of enzyme was also discussed.

关键词： protective additive g/L orthogonal experimental combination additive corresponding

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Functional characterization of a thermostable methionine adenosyltransferase from

Yanhui Liu,Biqiang Chen,Zheng Wang,Luo Liu,Tianwei Tan

《化学科学与工程前沿（英文）》 2016年第10卷第2期页码 238-244 doi: 10.1007/s11705-016-1566-2

摘要： MATTt (a thermostable methionine adenosyltransferase from HB27) was overexpressed in and purified using Ni-NTA affinity column. The enzymatic activity of MATTt was investigated in a temperature range from 30 °C to 90 °C, showing that MATTt exhibited a high enzymatic activity and good thermostability at 80 °C. Circular dichroism spectra reveals that MATTt contains high portion of -sheet structures contributing to the thermostability of MATTt. The kinetic parameter, is 4.19 mmol/L and 1.2 mmol/L for ATP and methionine, respectively. MATTt exhibits the highest enzymatic activity at pH 8. Cobalt (Co ) and zinc ion (Zn ) enhances remarkably the activity of MATTt compared to the magnesium ion (Mg ). All these results indicated that the thermostable MATTt has great potential for industry applications.

关键词： ion-preference methionine adenosyltransferase secondary structure thermostability Thermus thermophilus