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Safranines hold great promise as artificial flavin-like electron transfer cofactors with tunable properties. We have previously reported the stepwise synthesis of a safranine analogue, p-methoxy safranine. We now report an improved synthetic pathway which enables the synthesis of safranine analogues containing electron donating phenyl substituents. Low potential safranine analogues were synthesized that extend the range of two electron midpoint reduction potentials to 249 mV, or 11.4 kcal/mol. NMR analysis of the safranine series demonstrates that the 15N chemical shift at the N(5) position correlates with the two-electron reduction midpoint potential.  相似文献
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An artificial heme enzyme was created through self‐assembly from hemin and the lactococcal multidrug resistance regulator (LmrR). The crystal structure shows the heme bound inside the hydrophobic pore of the protein, where it appears inaccessible for substrates. However, good catalytic activity and moderate enantioselectivity was observed in an abiological cyclopropanation reaction. We propose that the dynamic nature of the structure of the LmrR protein is key to the observed activity. This was supported by molecular dynamics simulations, which showed transient formation of opened conformations that allow the binding of substrates and the formation of pre‐catalytic structures.  相似文献
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Understanding enzyme catalysis and developing ability to control of it are two great challenges in biochemistry. A few successful examples of computational‐based enzyme design have proved the fantastic potential of computational approaches in this field, however, relatively modest rate enhancements have been reported and the further development of complementary methods is still required. Herein we propose a conceptually simple scheme to identify the specific role that each residue plays in catalysis. The scheme is based on a breakdown of the total catalytic effect into contributions of individual protein residues, which are further decomposed into chemically interpretable components by using valence bond theory. The scheme is shown to shed light on the origin of catalysis in wild‐type haloalkane dehalogenase (wt‐DhlA) and its mutants. Furthermore, the understanding gained through our scheme is shown to have great potential in facilitating the selection of non‐optimal sites for catalysis and suggesting effective mutations to enhance the enzymatic rate.  相似文献
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Recent advances in computational design have enabled the development of primitive enzymes for a range of mechanistically distinct reactions. Here we show that the rudimentary active sites of these catalysts can give rise to useful chemical promiscuity. Specifically, RA95.5‐8, designed and evolved as a retro‐aldolase, also promotes asymmetric Michael additions of carbanions to unsaturated ketones with high rates and selectivities. The reactions proceed by amine catalysis, as indicated by mutagenesis and X‐ray data. The inherent flexibility and tunability of this catalyst should make it a versatile platform for further optimization and/or mechanistic diversification by directed evolution.  相似文献
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Rational design of enzymes is a stringent test of our understanding of protein structure and function relationship, which also has numerous potential applications. We present a novel method for enzyme design that can find good candidate protein scaffolds in a protein-ligand database based on vector matching of key residues. Residues in the vicinity of the active site were also compared according to a similarity score between the scaffold protein and the target enzyme. Suitable scaffold proteins were selected, and the side chains of residues around the active sites were rebuilt using a previously developed side-chain packing program. Triose phosphate isomerase (TIM) was used as a validation test for enzyme design. Selected scaffold proteins were found to accommodate the enzyme active sites and successfully form a good transition state complex. This method overcomes the limitations of the current enzyme design methods that use limited number of protein scaffold and based on the position of ligands. As there are a large number of protein scaffolds available in the Protein Data Band, this method should be widely applicable for various types of enzyme design.  相似文献
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The direct enantioselective addition of water to unactivated alkenes could simplify the synthesis of chiral alcohols and solve a long‐standing challenge in catalysis. Here we report that an engineered fatty acid hydratase can catalyze the asymmetric hydration of various terminal and internal alkenes. In the presence of a carboxylic acid decoy molecule for activation of the oleate hydratase from E. meningoseptica, asymmetric hydration of unactivated alkenes was achieved with up to 93 % conversion, excellent selectivity (>99 % ee, >95 % regioselectivity), and on a preparative scale.  相似文献
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糖苷酶作为一种重要的生物催化剂,在工业生物催化领域有着广阔的应用前景。但天然糖苷酶存在催化活性低、热稳定性和底物选择性差等缺点,严重限制了它在规模化生产中的推广应用。近年,有关糖苷酶催化机制与结构功能关系的研究备受关注,特别是计算机辅助酶设计在相关研究领域发挥着越来越重要的作用。本文综述了糖苷酶分子设计改造过程中应用的计算机辅助方法:包括同源比对、分子对接以及动力学模拟;系统阐述了这些计算方法在糖苷酶的结构与功能关系解析、酶催化分子机制、酶催化性能改造方面的应用现状。通过对上述方法的深入分析可以预见,计算机辅助方法将成为糖苷酶分子设计改造的重要手段,并且开发智能精准的计算分析方法将成为加快酶分子定向改造的新发展趋势。  相似文献
9.
The direct enantioselective addition of water to unactivated alkenes could simplify the synthesis of chiral alcohols and solve a long‐standing challenge in catalysis. Here we report that an engineered fatty acid hydratase can catalyze the asymmetric hydration of various terminal and internal alkenes. In the presence of a carboxylic acid decoy molecule for activation of the oleate hydratase from E. meningoseptica, asymmetric hydration of unactivated alkenes was achieved with up to 93 % conversion, excellent selectivity (>99 % ee, >95 % regioselectivity), and on a preparative scale.  相似文献
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