[Objectives]Laoshan black tea was subjected to supercritical CO_(2) extraction. [Methods]The extraction conditions of Laoshan black tea were studied by an orthogonal experiment and optimized by response surface method...[Objectives]Laoshan black tea was subjected to supercritical CO_(2) extraction. [Methods]The extraction conditions of Laoshan black tea were studied by an orthogonal experiment and optimized by response surface methodology. [Results] The optimum extraction conditions of black tea extract by supercritical CO_(2) extraction were as follows: extraction pressure 23.53 MPa, extraction time 1.73 h, and extraction temperature 49.75 ℃, with which the extract yield could reach 5.15% theoretically. [Conclusions] Based on the traditional extraction process, a supercritical extraction method optimized by response surface methodology and a unique extraction process were formed, which enriches the extraction processes and methods of natural raw materials.展开更多
Synthesis of chiral amines by amine dehydrogenase has the advantages of environmental friendliness,high stereoselectivity,and mild reaction conditions.However,amine dehydrogenase has low catalytic activity,which great...Synthesis of chiral amines by amine dehydrogenase has the advantages of environmental friendliness,high stereoselectivity,and mild reaction conditions.However,amine dehydrogenase has low catalytic activity,which greatly limits its application in the large-scale synthesis of chiral amines.In this study,a novel amine dehydrogenase was obtained by modifying the substrate specificity of leucine dehydrogenase via computer-aided protein engineering strategy.Furthermore,conservation analysis,homology modeling and molecular docking analysis were carried out via biocomputing strategy to select the mutation sites,and the mutants L52S and T143C were obtained.The enzyme activities of the two mutants to 2-pentanone were 1.55 U/mg and 2.06 U/mg,respectively.The enzyme activity of the latter was 188%and the Tm value was 2.55°Chigher than those of the original mutant,which laid a foundation for the efficient preparation of chiral amines by using this novel enzyme.展开更多
文摘[Objectives]Laoshan black tea was subjected to supercritical CO_(2) extraction. [Methods]The extraction conditions of Laoshan black tea were studied by an orthogonal experiment and optimized by response surface methodology. [Results] The optimum extraction conditions of black tea extract by supercritical CO_(2) extraction were as follows: extraction pressure 23.53 MPa, extraction time 1.73 h, and extraction temperature 49.75 ℃, with which the extract yield could reach 5.15% theoretically. [Conclusions] Based on the traditional extraction process, a supercritical extraction method optimized by response surface methodology and a unique extraction process were formed, which enriches the extraction processes and methods of natural raw materials.
基金supported by the Key Technology Research Plan Project of the Inner Mongolia Autonomous Region(2019GG302)the Program of the Key Laboratory of Carbohydrate Chemistry&Biotechnology,Ministry of Education,China(KLCCB-KF202103).
文摘Synthesis of chiral amines by amine dehydrogenase has the advantages of environmental friendliness,high stereoselectivity,and mild reaction conditions.However,amine dehydrogenase has low catalytic activity,which greatly limits its application in the large-scale synthesis of chiral amines.In this study,a novel amine dehydrogenase was obtained by modifying the substrate specificity of leucine dehydrogenase via computer-aided protein engineering strategy.Furthermore,conservation analysis,homology modeling and molecular docking analysis were carried out via biocomputing strategy to select the mutation sites,and the mutants L52S and T143C were obtained.The enzyme activities of the two mutants to 2-pentanone were 1.55 U/mg and 2.06 U/mg,respectively.The enzyme activity of the latter was 188%and the Tm value was 2.55°Chigher than those of the original mutant,which laid a foundation for the efficient preparation of chiral amines by using this novel enzyme.
