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Wild-type and molten globular chorismate mutase achieve comparable catalytic rates using very different enthalpy/entropy compensations 被引量:1
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作者 HU Hao 《Science China Chemistry》 SCIE EI CAS 2014年第1期156-164,共9页
The origin of the catalytic power of enzymes with a meta-stable native state,e.g.molten globular state,is an unsolved challenging issue in biochemistry.To help understand the possible differences between this special ... The origin of the catalytic power of enzymes with a meta-stable native state,e.g.molten globular state,is an unsolved challenging issue in biochemistry.To help understand the possible differences between this special class of enzymes and the typical ones,we report here computer simulations of the catalysis of both the well-folded wild-type and the molten globular mutant of chorismate mutase.Using the ab initio quantum mechanical/molecular mechanical minimum free-energy path method,we determined the height of reaction barriers that are in good agreement with experimental measurements.Enzyme-substrate interactions were analyzed in detail to identify factors contributing to catalysis.Computed angular order parameters of backbone N–H bonds and side-chain methyl groups suggested site-specific,non-uniform rigidity changes of the enzymes during catalysis.The change of conformational entropy from the ground state to the transition state revealed distinctly contrasting entropy/enthalpy compensations in the dimeric wild-type enzyme and its molten globular monomeric variant.A unique catalytic strategy was suggested for enzymes that are natively molten globules:some may possess large conformational flexibility to provide strong electrostatic interactions to stabilize the transition state of the substrate and compensate for the entropy loss in the transition state.The equilibrium conformational dynamics in the reactant state were analyzed to quantify their contributions to the structural transitions enzymes needed to reach the transition states.The results suggest that large-scale conformational dynamics make important catalytic contributions to sampling conformational regions in favor of binding the transition state of substrate. 展开更多
关键词 conformational entropy enthalpy entropy compensation enzyme evolution
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蛋白质的连接模型及机理研究
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作者 杨力权 桑鹏 李珍贵 《楚雄师范学院学报》 2013年第6期61-64,101,共5页
蛋白质是通过与其他蛋白质或生物分子的识别和连接来发挥功能的,阐明连接的驱动力及机理对理解蛋白质的功能发挥有很大帮助。文章对三种蛋白质连接的模型进行了描述和比较,对三种模型的驱动力和机理进行了研究,强调了蛋白质的连接是由... 蛋白质是通过与其他蛋白质或生物分子的识别和连接来发挥功能的,阐明连接的驱动力及机理对理解蛋白质的功能发挥有很大帮助。文章对三种蛋白质连接的模型进行了描述和比较,对三种模型的驱动力和机理进行了研究,强调了蛋白质的连接是由热力学的熵焓互补平衡控制的过程。 展开更多
关键词 蛋白质连接 连接机理 构象选择模型 吉布斯自由能 熵焓互补
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