二维过渡金属硫化物纳米复合材料的模拟酶特性及应用（英文）

纳米酶是一个非常令人兴奋和有希望的研究领域,旨在使用各种纳米材料模仿天然酶的一般原理,并在许多领域提供了大量实际应用.天然酶具有一些内在的缺点,如成本高、稳定性低、储存困难,以及催化活性对环境条件的敏感性.而纳米酶显示出低成本,高稳定性和高效活性.各种过氧化物酶和/或氧化酶模拟物已经取得了很大的进展.本综述介绍了关于二维过渡金属硫化物纳米复合材料的纳米酶特性的最新研究进展.     

综述与专论: 纳米酶在疾病治疗中的最新进展

纳米酶是具有酶催化活性的纳米材料,对比天然酶,纳米酶具有价格便宜、制备工艺简单、稳定性好、循环利用率高等优势.早期的纳米酶研究主要集中在检测方面,包括检测离子、小分子、核酸、蛋白、癌细胞等,随着对纳米酶的深入了解,研究人员发现纳米酶在疾病治疗领域也具有巨大的应用前景.本论文将介绍纳米酶在杀菌、抗氧化研究领域的最新研究进展.     

综述与专论: 纳米酶及其细胞活性氧调控

随着纳米技术的不断进步,人们逐渐开发出能够模拟天然抗氧化酶催化活性的无机纳米材料．这些纳米材料能够模拟过氧化物酶、过氧化氢酶、超氧化物歧化酶等天然酶的催化过程,从而调控细胞的氧化还原水平．本文从金属化合物、贵金属以及碳基纳米酶的角度,阐述了它们对细胞内活性氧(ROS)的调控作用以及在各种氧化应激相关疾病治疗中的应用．作为一种新型的模拟酶,纳米酶有望在生物医学领域中为疾病治疗提供一种新的策略．     

基于纳米酶的比色生物传感器在生物医学检测中的应用

比色生物传感技术由于具有灵敏度高、方法简单并且容易操作等优点，已广泛应用于生物环境中污染物检测、生物体内重要标志物的检测以及癌症筛查等多个领域。基于纳米酶的比色生物传感器主要是借助纳米酶自身所具有的催化能力，模拟类过氧化物酶活性，将显色剂氧化生成有色溶液，从而实现可视化检测，并通过对有色溶液吸光度的检测得到相关物质的含量。与无纳米酶的比色生物传感器相比，基于纳米酶的比色生物传感器具有选择性更高、检测更快以及灵敏度更高等优点。纳米酶在具有天然酶活性的同时还具有成本低、稳定性好的、易于合成等优点，其相关研究越来越广泛。目前，基于纳米酶的比色生物传感器已成为辅助相关医学检测的重要方法，同时也广泛应用于便携和实时性相关检测当中，为医学检测提供了重要的支持和保障。为了提高比色生物传感器的灵敏度以及应用范围，研究人员也在致力于增加可检测物质的种类以及纳米酶种类的多样化等。本文主要介绍基于纳米酶的比色生物传感器的检测原理、几类典型的纳米酶，以及基于纳米酶的比色生物传感器在生物医学检测领域中的应用情况和研究进展。     

纳米酶在疾病治疗中的最新进展

纳米酶是具有酶催化活性的纳米材料,对比天然酶,纳米酶具有价格便宜、制备工艺简单、稳定性好、循环利用率高等优势.早期的纳米酶研究主要集中在检测方面,包括检测离子、小分子、核酸、蛋白质、癌细胞等,随着对纳米酶的深入了解,研究人员发现纳米酶在疾病治疗领域也具有巨大的应用前景.本论文将介绍纳米酶在细菌感染、炎症、癌症、神经退行性疾病等治疗领域的最新研究进展.     

纳米材料固定化酶的研究进展

近年来,纳米技术为酶固定化提供了多种纳米级材料,纳米材料固定化酶不仅具有高的酶负载量,而且具有良好的酶稳定性。本文基于纳米材料固定化酶,对纳米材料的种类进行了总结,分析了纳米材料对固定化酶性能的影响,并介绍了纳米级固定化方法及纳米材料固定化酶在生物转化、生物传感器、生物燃料电池等领域的应用。     

基于纳米酶的无抗生素抗菌策略

抗生素是抵抗细菌感染的有力武器，然而抗生素的过量使用和滥用加速了细菌耐药性的发展，严重威胁人类健康。开发高效和广谱的无抗生素抗菌策略迫在眉睫。以过氧化氢(H₂O₂)为代表的活性氧(reactive oxygen species, ROS)能氧化多种生物分子，使其结构和活性改变而发挥广谱抗菌作用，是无抗生素抗菌策略之一。然而，临床常用的H₂O₂浓度较高(0.5%～3%),会刺激皮肤和延缓伤口愈合。利用过氧化物酶催化H₂O₂生成氧化性更强的羟自由基(·OH),可大幅提高ROS抗菌策略的性能。然而，天然酶生产成本高、稳定性低等缺点限制了该策略的推广。纳米酶是具有类似天然酶催化活性的纳米材料的统称。与天然酶相比，纳米酶具有制备简单、成本低和易储存等优势，是开发基于ROS的无抗生素抗菌策略的良好选择。贵金属、金属氧化物、金属硫化物、金属有机框架、碳基纳米材料等多种纳米材料具有过氧化物酶、氧化酶等的模拟催化活性，基于这些材料的纳米酶抗菌研究层出不穷，本文将对这些研究进...     

综述——新型纳米生物材料的研发：纳米酶的发现与应用

自2007年发现四氧化三铁纳米材料具有类似辣根过氧化物酶的催化特性以来,纳米酶研究领域迅速崛起．不同形貌、尺度和材料各异的纳米酶相继出现,同时其催化机制逐渐被认识．由于纳米酶具有催化效率高、稳定、经济和规模化制备的特点,它在医学、化工、食品、农业和环境等领域的应用研究便应运而生．纳米酶的发现,不仅推动了纳米科技的基础研究,还拓展了纳米材料的应用．本文将介绍纳米酶研究领域的最新研究进展．     

综述与专论: 纳米酶在分析化学中的应用研究：从体外检测到活体分析

纳米酶是指具有类酶催化活性的纳米材料．近年来,纳米酶研究引起了人们的极大兴趣．纳米酶已被广泛应用于诸如生物传感、生物成像、疾病治疗和环境保护等众多领域．在本综述中,我们将着重讨论纳米酶在分析化学领域的研究进展．首先将讨论纳米酶在体外检测的应用,将包括生物活性小分子、核酸、蛋白质类生物标志物、细胞等的检测．其后将讨论纳米酶在活体分析的应用,将包括监测活脑、肿瘤组织等的生物活性小分子、药物的药效、药物与纳米酶的代谢等．最后,我们将讨论纳米酶应用于分析化学时面临的挑战和未来研究前景．     

Mn_3O_4纳米酶用于活体炎症治疗

正纳米酶(nanozyme)是指具有类似天然酶活性的纳米材料.与天然酶相比,纳米酶具有稳定性高、催化活性可调、易于大规模制备和储存,有利于进行表面修饰等特点,因而受到研究人员的广泛关注.自阎锡蕴及合作者[1]于2007年报道首例基于四氧化三铁纳米酶     

Engineered whole-cell biocatalyst-based detoxification and detection of neurotoxic organophosphate compounds

The development of efficient tools is required for the eco-friendly detoxification and effective detection of neurotoxic organophosphates (OPs). Although enzymes have received significant attention as biocatalysts because of their high specific activity, the uneconomic and labor-intensive processes of enzyme production and purification make their broad use in practical applications difficult. Because whole-cell systems offer several advantages compared with free enzymes, including high stability, a reduced purification requirement, and low preparation cost, they have been suggested as promising biocatalysts for the detoxification and detection of OPs. To develop efficient whole-cell biocatalysts with enhanced activity and a broad spectrum of substrate specificity, several factors have been considered, namely the selected strains, the chosen OP-hydrolyzing enzymes, where enzymes are localized in a cell, and which enhancer will assist the expression, function, and folding of the enzyme. In this article, we review the current investigative progress in the development of engineered whole-cell biocatalysts with excellent OP-hydrolyzing activity, a broad spectrum of substrate specificity, and outstanding stability for the detoxification and detection of OPs.     

综述与专论: 纳米酶在疾病诊断中的应用

纳米酶是近年来我国科学家发现的一类自身蕴含酶学特性的纳米材料。作为一种新型人工模拟酶,纳米酶具有经济、稳定、易于大批量生产的优势. 更重要的是,纳米酶是一个双功能或者多功能的分子,它不仅具有催化活性,还兼有纳米材料特有的物理和化学性质,如磁性、荧光、光热特性等. 纳米酶的出现为酶催化反应在疾病诊断中的应用提供了新思路,新方法和新工具. 本文将重点介绍近几年纳米酶在疾病诊断方面的应用,涵盖了癌症、代谢性疾病、传染性疾病、神经退行性疾病、心血管疾病和炎症性疾病等不同疾病类型,并对该领域未来的发展方向进行了讨论和展望.     

Carbon nanotubes tuned foam structures as novel nanostructured biocarriers for lignocellulose hydrolysis

The use of immobilized enzymes during saccharification of lignocelluloses enables the continuous process of enzymatic hydrolysis and repeatable use of enzyme, resulting in reduced operational cost. Novel nano-biocarriers were developed by layer-by-layer deposition of carbon nanotube (CNT) on the foam structures, and their efficiency for enzyme immobilization was demonstrated with cellulase and β-glucosidase. A three-fold enhancement was achieved in the activity of cellulase immobilized on CNT coated polyurethane foam. In addition, both cellulase and β-glucosidase immobilized on the CNT-foam showed much better storage stability and operational stability than the ones immobilized on the commercial biocarrier (Celite), which is critical for a continuous operation. CNT coated monolith was also developed as a biocarrier, offering high surface area and geometric stability. These nano-biocarriers are promising candidates for the efficient saccharification of biomass and to reduce carbon footprint and cost of the equipment.     

Potential applications of enzymes immobilized on/in nano materials: A review

Several new types of carriers and technologies have been implemented in the recent past to improve traditional enzyme immobilization which aimed to enhance enzyme loading, activity and stability to decrease the enzyme biocatalyst cost in industrial biotechnology. These include cross-linked enzyme aggregates, microwave-assisted immobilization, click chemistry technology, mesoporous supports and most recently nanoparticle-based immobilization of enzymes. The union of the specific physical, chemical, optical and electrical properties of nanoparticles with the specific recognition or catalytic properties of biomolecules has led to their appearance in myriad novel biotechnological applications. They have been applied time and again for immobilization of industrially important enzymes with improved characteristics. The high surface-to-volume ratio offered by nanoparticles resulted in the concentration of the immobilized entity being considerably higher than that afforded by experimental protocols based on immobilization on planar 2-D surfaces. Enzymes immobilized on nanoparticles showed a broader working pH and temperature range and higher thermal stability than the native enzymes. Compared with the conventional immobilization methods, nanoparticle based immobilization served three important features; (i) nano-enzyme particles are easy to synthesize in high solid content without using surfactants and toxic reagents, (ii) homogeneous and well defined core-shell nanoparticles with a thick enzyme shell can be obtained, and (iii) particle size can be conveniently tailored within utility limits. In addition, with the growing attention paid to cascade enzymatic reaction and in vitro synthetic biology, it is possible that co-immobilization of multi-enzymes could be achieved on these nanoparticles.     

Enzymatic activity of Lecithin:retinol acyltransferase: A thermostable and highly active enzyme with a likely mode of interfacial activation

Lecithin:retinol acyltransferase (LRAT) plays a major role in the vertebrate visual cycle. Indeed, it is responsible for the esterification of all-trans retinol into all-trans retinyl esters, which can then be stored in microsomes or further metabolized to produce the chromophore of rhodopsin. In the present study, a detailed characterization of the enzymatic properties of truncated LRAT (tLRAT) has been achieved using in vitro assay conditions. A much larger tLRAT activity has been obtained compared to previous reports and to an enzyme with a similar activity. In addition, tLRAT is able to hydrolyze phospholipids bearing different chain lengths with a preference for micellar aggregated substrates. It therefore presents an interfacial activation property, which is typical of classical phospholipases. Furthermore, given that stability is a very important quality of an enzyme, the influence of different parameters on the activity and stability of tLRAT has thus been studied in detail. For example, storage buffer has a strong effect on tLRAT activity and high enzyme stability has been observed at room temperature. The thermostability of tLRAT has also been investigated using circular dichroism and infrared spectroscopy. A decrease in the activity of tLRAT was observed beyond 70 °C, accompanied by a modification of its secondary structure, i.e. a decrease of its α-helical content and the appearance of unordered structures and aggregated β-sheets. Nevertheless, residual activity could still be observed after heating tLRAT up to 100 °C. The results of this study highly improved our understanding of this enzyme.     

Production of α-amylase in a low cost medium by Bacillus licheniformis TCRDC-B13

A low cost synthetic medium producing large quantities of α-amylase has been developed. Bacillus licheniformis TCRDC-B13 isolated from soil was used for α-amylase production. The α-amylase enzyme of this strain showed excellent stability at high temperatures and over a wide pH range. The low cost medium produced 5 times more enzyme than the high cost synthetic medium (using yeast extract and peptone) in shake flasks. In a 2.6-l fermentor, the enzyme production further doubled.     

Incorporation of styrene enhances recognition of ribonuclease A by molecularly imprinted polymers

Ribonuclease A (RNase A) is an RNA-cleaving enzyme characterized by its high conformational stability and strong catalytic activity. This enzyme is ubiquitous in living organisms and is difficult to inactivate. In polymerase chain reaction (PCR) RNase activity is removed by adding inhibitors. Molecularly imprinted polymers (MIPs) with high selectivity, high stability, low cost and facile synthesis could prove useful in extraction of target molecules, such as RNase A, from reaction mixtures. In this investigation, MIPs were synthesized from the monomers styrene and polyethyleneglycol 400 dimethacrylate (PEG400DMA) in several different ratios. Styrene as a functional monomer gave MIPs with a higher affinity for RNase A than other functional monomers tested, according to both enzyme-linked immnuosorbent assay (ELISA) and isothermal titration calorimetry (ITC). The optimum volume ratio of styrene/PEG400DMA was 20/100 at 25 degrees C, and this ratio maximized the rebinding efficiency of RNase A to MIPs. Isothermal titration calorimetry was also used, and could be useful to design the composition of molecularly imprinted polymers for various target molecules.     

Structural prediction and comparative docking studies of psychrophilic ��- Galactosidase with lactose, ONPG and PNPG against its counter parts of mesophilic and thermophilic enzymes

Enzymes from psychrophiles catalyze the reactions at low temperatures with higher specific activity. Among all the psychrophilic enzymes produced, cold active β-galactosidase from marine psychrophiles revalorizes a new arena in numerous areas at industrial level. The hydrolysis of lactose in to glucose and galactose by cold active β-galactosidase offers a new promising approach in removal of lactose from milk to overcome the problem of lactose intolerance. Herein we propose, a 3D structure of cold active β-galactosidase enzyme sourced from Pseudoalteromonas haloplanktis by using Modeler 9v8 and best model was developed having 88% of favourable region in ramachandran plot. Modelling was followed by docking studies with the help of Auto dock 4.0 against the three substrates lactose, ONPG and PNPG. In addition, comparative docking studies were also performed for the 3D model of psychrophilic β-galactosidase with mesophilic and thermophilic enzymes. Docking studies revealed that binding affinity of enzyme towards the three different substrates is more for psychrophilic enzyme when compared with mesophilic and thermophilic enzymes. It indicates that the enzyme has high specific activity at low temperature when compared with mesophilic and thermophilic enzymes.     

Heat stability and pH activity data of alpha-L-fucosidase in human serum vary with enzyme concentration

alpha-L-Fucosidase from serum of humans with either high or low enzyme activity was separately purified. the enzyme from either source had virtually the same heat stability and pH activity profile. It has been widely reported that alpha-L-fucosidase in crude sera from individuals with high and low enzyme activity differed with respect to heat stability and activity at pH 4 relative to activity at pH 5, the pH optimum of the enzyme. We investigated this discrepancy and found that both the heat stability and relative activity at pH 4 of alpha-L-fucosidase from sera with either high or low enzyme activity was dependent upon enzyme concentration. With decreasing enzyme concentration, the enzyme was more heat labile and had less relative activity at pH 4. Consequently, if the data obtained using high and low enzyme activity sera are compared on the basis of equivalent amounts of serum instead of equivalent amounts of enzyme activity, differences between the enzyme from high and low activity serum would be erroneously inferred. Apparently, this is what other investigators have done. Moreover, we found that alpha-L-fucosidase can exist in heat-stable or labile species with sedimentation coefficients of 9.8 S and 4.8 S, respectively. The interconversion and relative proportion of these species is dependent upon enzyme concentration and pH.