Enabling highly (R)-enantioselective epoxidation of styrene by engineering unique non-natural P450 peroxygenases

Unlike the excellent (S)-enantioselective epoxidation of styrene performed by natural styrene monooxygenases (ee > 99%), the (R)-enantioselective epoxidation of styrene has not yet achieved a comparable efficiency using natural or engineered oxidative enzymes. This report describes the H₂O₂-dependent (R)-enantioselective epoxidation of unfunctionalized styrene and its derivatives by site-mutated variants of a unique non-natural P450BM3 peroxygenase, working in tandem with a dual-functional small molecule (DFSM). The observed (R)-enantiomeric excess (ee) of styrene epoxidation is up to 99% with a turnover number (TON) of 918 by the best enantioselective mutant F87A/T268I/L181Q, while the best active mutant F87A/T268I/V78A/A184L (with 98% ee) gave a catalytic TON of 4350, representing the best activity of a P450 peroxygenase towards styrene epoxidation to date. Following this approach, a set of styrene derivatives, such as o-, m-, p-chlorostyrenes and fluorostyrenes, could also be epoxidized with modest to very good TONs (362–3480) and high (R)-enantioselectivities (95–99% ee). The semi-preparative scale synthesis of (R)-styrene oxide performed at 0 °C with high conversion, maintaining enantioselectivity, and moderate isolated yields, further suggests the potential application of the current P450 enzymatic system in styrene epoxidation. This study indicates that the synergistic use of protein engineering and an exogenous DFSM constitutes an efficient strategy to control the enantioselectivity of styrene epoxidation, thus substantially expanding the chemical scope of P450 enzymes as useful bio-oxidative catalysts.

H₂O₂-dependent epoxidation of unfunctionalized styrenes is achieved with high (R)-enantioselectivity and moderate to excellent TONs by combining site-mutated variants of cytochrome P450BM3 monooxygenase and a dual-functional small molecule (DFSM).     

Dual‐Functional Small Molecules for Generating an Efficient Cytochrome P450BM3 Peroxygenase

We report a unique strategy for the development of a H₂O₂‐dependent cytochrome P450BM3 system, which catalyzes the monooxygenation of non‐native substrates with the assistance of dual‐functional small molecules (DFSMs), such as N‐(ω‐imidazolyl fatty acyl)‐l ‐amino acids. The acyl amino acid group of DFSM is responsible for bounding to enzyme as an anchoring group, while the imidazolyl group plays the role of general acid–base catalyst in the activation of H₂O₂. This system affords the best peroxygenase activity for the epoxidation of styrene, sulfoxidation of thioanisole, and hydroxylation of ethylbenzene among those P450–H₂O₂ system previously reported. This work provides the first example of the activation of the normally H₂O₂‐inert P450s through the introduction of an exogenous small molecule. This approach improves the potential use of P450s in organic synthesis as it avoids the expensive consumption of the reduced nicotinamide cofactor NAD(P)H and its dependent electron transport system. This introduces a promising approach for exploiting enzyme activity and function based on direct chemical intervention in the catalytic process.     

线粒体体外代谢热动力学模型及其演化优化研究

导出了线粒体体外代谢的热动力学方程，探讨了它和指数模型的关系，将演化计算技术引入生物热化学领域，用ＭＴＤ方程和演化计算技术，对文献报导的八种鱼肝线粒体体外代谢的热动力学参数进行了全局优化。     

Liquid crystalline phase of G-tetrad DNA for NMR study of detergent-solubilized proteins

The liquid crystalline phase consisting of the potassium salt of the dinucleotide d(GpG) is compatible with detergents commonly used for solubilizing membrane proteins, including dodecylphosphocholine, the lysolipid 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine, and small bicelles consisting of dihexanoyl phosphatidylcholine and dimyristoyl phosphatidylcholine. The chiral nematic liquid crystalline phase of d(GpG) consists of long columns of stacked G-tetrad structures and carry a net negative charge. For water-soluble systems, the protein alignment induced by d(GpG) is very similar to that observed for liquid crystalline Pf1 bacteriophage, but of opposite sign. Alignment of the detergent-solubilized fusion domain of hemagglutinin is demonstrated to be homogeneous and stable, resulting in high quality NMR spectra suitable for the measurement of residual dipolar couplings.     

Tuning Interfacial Structures for Better Catalysis of Water Electrolysis

Interface modulation, as an old concept of heterogeneous catalysis, represents an emerging, fast-growing and exciting direction in the field of water electrolysis. Over the past five years, diverse hetero-nanostructures have been synthesised as water electrolysis catalysts by taking advantage of interface modulation. However, it seems that the performance (i.e., efficiency and durability) of these materials needs to be further improved. Therefore, a comprehensive summary of recent achievements and the challenging issues concerning the regulation of material functionalities through interface modulation is necessary and helpful. Herein, firstly, the fundamentals of water electrolysis are outlined, and then the delicate design and fine control of well-defined interfaces, as well as related mechanisms for performance improvement are discussed. Finally, future opportunities and challenges in the everlasting pursuit of highly efficient and robust water electrolysis catalysts are highlighted.     

Precise Control Over Kinetics of Molecular Assembly: Production of Particles with Tunable Sizes and Crystalline Forms

It has been long‐pursued but remains a challenge to precisely manipulate the molecular assembly process to obtain desired functional structures. Reported here is the control over the assembly of solute molecules, by a programmed recrystallization of solvent crystal grains, to form micro/nanoparticles with tunable sizes and crystalline forms. A quantitative correlation between the protocol of recrystallization temperature and the assembly kinetics results in precise control over the size of assembled particles, ranging from single‐atom catalysts, pure drug nanoparticles, to sub‐millimeter organic‐semiconductor single crystals. The extensive regulation of the assembly rates leads to the unique and powerful capability of tuning the stacking of molecules, involving the formation of single crystals of notoriously crystallization‐resistant molecules and amorphous structures of molecules with a very high propensity to crystallize, which endows it with wide‐ranging applications.     

A necessary and sufficient condition of positive solutions for nonlinear singular differential systems with four-point boundary conditions

In this paper, we concert with the existence of positive solution for the following nonlinear singular differential system with four-point boundary conditions

     

负载芳基苄醚树枝形酞菁锌聚合物纳米粒子的合成及其离体光动力活性

首先将对氰基溴化苄与3,5-二羟基苯甲醇通过Frétchet反应合成芳基苄醚树枝分子3,5[二-(4'-氰基苯甲氧基)]苯甲醇(1),1与4-硝基邻苯二甲腈合成前驱物4-{3',5'-[二-(4"-氰基苯甲氧基)]}苯甲氧基邻苯二甲腈(3),然后3在乙酸锌,1,8-二氮杂二环(5,4,0)-7-十一烯(DBU)和正戊醇...