利用同源建模、分子模拟和分子对接技术分析家蚕中碳酸酐酶的结构和催化机制

该研究以来源于家蚕的碳酸酐酶为研究对象,利用同源建模建立了家蚕碳酸酐酶的三维结构并预测了其潜在的活性区域。随后,利用Autodock-Vina对家蚕碳酸酐酶和底物进行分子对接,分析和评价了对接模型以及与乙酸对硝基苯酯底物对接过程中的相互作用。经分子动力学模拟和MM/PBSA,分析催化过程中家蚕碳酸酐酶的均方根偏差、溶剂可及面积以及径向分布函数。结果表明：建模所得的酶结构可靠性良好(完全允许区域为89.3%,允许区域10.3%,总和超过了99%);家蚕碳酸酐酶与底物的对接结合能为-6.1 Kcal/mol;范德华力在家蚕碳酸酐酶和底物的结合中占主导地位,而极性溶剂化对结合有显著的反作用;家蚕碳酸酐酶与底物的相互作用的区域为：138L～150V和209L～217C;同源建模所得的家蚕碳酸酐酶结构稳定(模拟最后50 ns RMSD值约0.35 nm)。该研究对后续进一步理性设计和改造家蚕碳酸酐酶提供了一定的理论支持。     

食品中生物胺含量及生物胺氧化酶的研究进展

生物胺是一类具有潜在毒性的生物活性物质,在食品中广泛存在。生物胺氧化酶是广泛存在于动植物、微生物体内的,能够将已生成的生物胺分解成相应的醛、氨气和过氧化氢的一类酶,该类酶在降解食品中生物胺方面具有良好的应用前景。本文将从食品中生物胺含量以及生物胺氧化酶的分类、影响因素、产生菌株、降解特性等方面进行综述。     

补锌饮料的研制

一、前言 锌是人体的基本营养之一,是健康所必需的一种重要微量元素,它是DNA、RNA聚合酶、胸腺嘧啶核苷激酶、碳酸酐酶、碱性磷酸酶,谷氨酸脱氢酶、乳酸脱氢酶等一百多种酶的组成部分或激活因子。它通过“激活”这些酶发挥正常的生理功能,直接参与核酸及蛋白质的合成。分解代谢酶缺乏时,能抑制DNA与RNA聚合酶的活性,从而明显地降     

纳米二氧化铈模拟过氧化物酶的研究进展

过氧化物酶在自然界中广泛分布,其利用过氧化氢来催化各种有机和无机化合物的氧化,在诸多领域得以应用。但由于过氧化物酶属于生物有机材料,存在纯化困难、稳定性差等缺点,也限制了其应用环境。纳米酶作为一种高效、简单、稳定、高性能的天然酶替代物在各种应用中得到了广泛的研究,克服了天然酶在工业等方面的实际局限性,其中纳米二氧化铈（CeO₂NPs）由于具有过氧化物酶特性已成为科学界研究的热点之一。本文综述了近几年纳米二氧化铈模拟过氧化物酶在食品分析、生物标志物的检测、医学、光学传感、仿生等方面应用的研究进展,显示出它在不同研究领域的巨大潜力,希望能为后续进一步研究提供一定的参考。     

酶在果汁加工中的应用研究进展

酶是生物催化剂,它在果汁加工中的应用日益广泛。综合介绍酶提高果汁出汁率、澄清度、抑制果汁褐变、果汁脱苦、增香方面的应用进展。     

补锌饮料的研制

<正> 一、前言 锌是人体的基本营养之一,是健康所必需的一种重要微量元素,它是DNA、RNA聚合酶、胸腺嘧啶核苷激酶、碳酸酐酶、碱性磷酸酶,谷氨酸脱氢酶、乳酸脱氢酶等一百多种酶的组成部分或激活因子。它通过“激活”这些酶发挥正常的生理功能,直接参与核酸及蛋白质的合成。分解代谢酶缺乏时,能抑制DNA与RNA聚合酶的活性,从而明显地降      

漆酶及其应用

漆酶是一种含铜多酚氧化酶,具有催化氧化酚型底物的能力.漆酶在很多领域得到了广泛的应用.本文主要从纸浆的生物漂白、生物制浆、去除氯酚类化合物的毒性等几个方面进行了介绍.     

采用生物工艺 缩短酿造时间

日本采用生物工艺方法酿造酒、酱油、豆酱菜,大大缩短工期,正在广泛利用中.其秘密是利用“生物反应炉”,将生产过程中活跃的菌和酶固定在膜或陶瓷体上,配置得当,再放入原料,制成成品.这种方法即可缩短工期,又可连续生产.     

非水介质中脂肪酶催化合成酯类的研究进展

生物催化是酶工程学的研究重点之一。脂肪酶的来源广泛,底物特异性多样化,它在生物催化中的研究和应用尤为引人注目,利用脂肪酶合成酯类已成为研究的热点之一。本文综述了脂肪酶在有机相溶剂中催化酯类合成的反应机理、相对于化学合成酶法合成的优点以及脂肪酶合成酯类的研究进展。并探索提出了改进该方法的一些想法,以期使酶合成法可以逐步取代化学合成法。      

酶基生物传感器在快速检测中的研究进展

酶基生物传感器是一种以酶作为生物识别元件的生物传感器, 具有灵敏度高、专一性强、检测限低、选择性好、操作简单、便于携带和可室外在线连续监测等优点, 是最早实现商品化的一类生物传感器。目前, 酶基生物传感器研究广泛并已成功应用于各个领域, 包括环境监测、食品安全检验、生物医学检验等领域。随着环境污染、食品安全等问题的加剧, 现场快速检测技术的需求不断增大。因此, 研究酶基生物传感器具有重要的意义。本文介绍了酶基生物传感器, 阐述了酶基生物传感器的相关概念和原理, 总结了电化学酶基生物传感器、光学酶基生物传感器和其他酶基生物传感器在快速检测中的研究现状, 并展望了酶基生物传感器未来的研究方向。     

Embryonic exposure to oestrogen causes eggshell thinning and altered shell gland carbonic anhydrase expression in the domestic hen

Eggshell thinning among wild birds has been an environmental concern for almost half a century. Although the mechanisms for contaminant-induced eggshell thinning are not fully understood, it is generally conceived to originate from exposure of the laying adult female. Here we show that eggshell thinning in the domestic hen is induced by embryonic exposure to the synthetic oestrogen ethynyloestradiol. Previously we reported that exposure of quail embryos to ethynyloestradiol caused histological changes and disrupted localization of carbonic anhydrase in the shell gland in the adult birds, implying a functional disturbance in the shell gland. The objective of this study was to examine whether in ovo exposure to ethynyloestradiol can affect eggshell formation and quality in the domestic hen. When examined at 32 weeks of age, hens exposed to ethynyloestradiol in ovo (20 ng/g egg) produced eggs with thinner eggshells and reduced strength (measured as resistance to deformation) compared with the controls. These changes remained 14 weeks later, confirming a persistent lesion. Ethynyloestradiol also caused a decrease in the number of shell gland capillaries and in the frequency of shell gland capillaries with carbonic anhydrase activity. These data suggested that a disrupted carbonic anhydrase expression was involved in the mechanism for the oestrogen-induced eggshell thinning found in this study. The results support our hypothesis that eggshell thinning in avian wildlife can result from a structural and functional malformation in the shell gland, induced by xeno-oestrogen exposure during embryonic development.     

普通烟草碳酸酐酶家族基因的生物信息学分析

为挖掘普通烟草碳酸酐酶基因的信息并探讨其功能,本研究利用生物信息学方法,在烟草基因组数据库中对普通烟草碳酸酐酶家族成员进行了检索,并对其理化性质、遗传进化、基因结构、蛋白保守基序、顺式作用元件和组织表达模式进行了分析。结果显示,在普通烟草中至少含有9个α和6个β亚家族成员。在进化关系上,不同亚家族成员之间,序列同源性较低;与水稻相比,拟南芥和普通烟草两个亚家族间的亲缘关系较近。亚细胞定位分析结果显示,烟草α亚家族成员在细胞壁、细胞膜、线粒体、叶绿体、细胞质等细胞器中均有分布,而β亚家族成员均存在于叶绿体中。基因结构和保守基序分析说明,各亚家族成员的基因结构和蛋白保守基序呈现较高的一致性。启动子顺式作用元件分析显示,烟草碳酸酐酶基因的启动子中,均含有多个参与光反应、激素响应、非生物胁迫和机械损伤等相关的顺式作用元件。基因组织表达模式分析表明,烟草的碳酸酐酶基因不同成员在不同组织表达水平存在差异,并呈现出时空特异性。本研究结果为烟草碳酸酐酶基因的功能研究奠定了基础。     

烟草SOC1基因的克隆和表达分析

SUPPRESSOR OF OVEREXPRESSION OF CONSTANTS 1（SOC1）基因属MADS-box转录因子家族,在植物成花诱导过程中起关键作用,但在营养生长过程中的调控功能还未获得充分研究。为明确SOC1基因在叶片中的生理作用,克隆到烟草中SOC1基因的完整开放阅读框,全长806bp。农杆菌介导转化烟草后,获得26棵转基因植株,其中23棵鉴定为阳性植株,转化率为88.46%。与野生型烟草K326相比,获得的SOC1过表达烟株开花提前,株高增加,叶片宽大。半定量RT-PCR结果显示,SOC1过表达不影响叶片中Rubisco大亚基、蔗糖磷酸合成酶和蔗糖合成酶基因的表达水平,但提高了抗坏血酸氧化酶的表达水平;提高了碳酸酐酶活性、蔗糖含量和还原性抗坏血酸含量,并降低了抗坏血酸过氧化物酶活性。表明SOC1可能通过影响叶片抗坏血酸库的氧化还原状态而提高碳酸酐酶活性和光合速率。      

Borate-catalyzed carbon dioxide hydration via the carbonic anhydrase mechanism

The hydration of CO(2) plays a critical role in carbon capture and geoengineering technologies currently under development to mitigate anthropogenic global warming and in environmental processes such as ocean acidification. Here we reveal that borate catalyzes the conversion of CO(2) to HCO(3)(-) via the same fundamental mechanism as the enzyme carbonic anhydrase, which is responsible for CO(2) hydration in the human body. In this mechanism the tetrahydroxyborate ion, B(OH)(4)(-), is the active form of boron that undergoes direct reaction with CO(2). In addition to being able to accelerate CO(2) hydration in alkaline solvents used for carbon capture, we hypothesize that this mechanism controls CO(2) uptake by certain saline bodies of water, such as Mono Lake (California), where previously inexplicable influx rates of inorganic carbon have created unique chemistry. The new understanding of CO(2) hydration provided here should lead to improved models for the carbon cycle in highly saline bodies of water and to advances in carbon capture and geoengineering technology.     

不同孵化时期鸡蛋蛋清小分子多肽的鉴定及功能分析

通过聚丙烯酰胺凝胶电泳(SDS-PAGE)和基质辅助激光解吸电离飞行时间串联质谱(MALDI-TOF MS/MS)技术,比较不同孵化时期鸡胚蛋蛋清中产生的小分子多肽,研究肽段与鸡胚发育之间的联系。结果显示在孵化第0、6、14、16 d分别得到837、879、872和842条肽段(共3430条)。除丛生蛋白肽段外,大部分被鉴定到的肽段来源于蛋清中低丰度蛋白。其中926条肽段来源于与鸡胚先天免疫有关的9种蛋白质,如防御素、白细胞介素6等;256条肽段来源于与鸡胚呼吸系统发育相关的3种蛋白质,cx9C基序蛋白、sprouty蛋白和碳酸酐酶。结果表明由蛋清蛋白质内源性酶降解形成的小分子多肽可能对鸡胚发育时形成的呼吸和免疫系统等发挥重要作用。     

Effect of exogenous zinc deficiency on the duration of skin graft functioning

The influence of alimentary zinc deficiency on duration of skin allograft functioning was studied in experiments on guinea pigs. Feeding the animals with a ration deprived of zinc results in significant prolongation of the skin graft functioning period. Thus, in the test group animals that received the ration deprived of zinc the mean time of the graft functioning comprised 24.0 +/- 1.4 days, while in the guinea pigs of the control group that were fed with full value ration, this parameter was 9.9 +/- 0.42 days. At the same time the number of circulating lymphocytes was decreased and their capacity for spontaneous rosette-formation was suppressed in the peripheral blood of the test group animals, as well as manifest inhibition of zinc-dependent enzymes (lactate dehydrogenase, alkaline phosphatase, carbonic anhydrase) in the blood was recorded. Zinc deficiency in the ration induces significant diminution of this trace element content in the muscles, bones, liver, skin and blood, under conditions of its daily negative balance in the body.     

Determination of changes in protein conformation caused by pH and temperature

Protein denaturation has a major impact on meat quality parameters such as water holding capacity, tenderness and color. Specific information about structural changes of the individual muscle proteins post-mortem could help understand the factors affecting meat quality. An aromatic dye, 4,4′-dianilino-1,1′-binaphthyl-5,5′-disulfonic acid (bisANS) that binds to the hydrophobic patches of proteins was used to monitor changes in the conformation of individual sarcoplasmic proteins caused by pH. The bisANS reagent was covalently linked to the proteins with UV-light and the proteins were separated and identified using gel electrophoresis and mass spectrometry. The results showed that the sarcoplasmic proteins creatine kinase M, aldolase A and lactate dehydrogenase showed increased hydrophobicity whereas carbonic anhydrase III showed decreased hydrophobicity with increasing pH. Temperature only had a marked effect on the results at around 40 °C, there being no change between 25 and 35 °C.     

Insights from proteome to phosphorylated proteome: deciphering different regulatory mechanisms in goat muscles with high- and low-meat quality

To investigate the inner mechanisms of meat quality differences between high-quality (HQ) and low-quality (LQ), a comparative quantitative study between longissimus thoracis and external intercostals of goat muscle was performed from proteome to phosphorylated proteome using RP-HPLC in combination with the ‘isobaric tag’ for relative and absolute quantitation (iTRAQ) labelling strategy. Altogether, 1441 proteins were identified in our study, of which 673 were phosphoproteins, and a total of twenty were common differentially expressed proteins. Myosin, carbonic anhydrase, and phosphoglucomutase could be used as proteins marker for HQ and LQ meat. Bioinformatics analysis showed that these proteins exhibited different rates for glycolysis and oxidative phosphorylation reaction, thus causing the different pH and NADH change rates, and resulting in better colour, tenderness, and water retention in HQ meat. The release of Ca²⁺ and adenosine triphosphate changed the meat quality through calcium signalling. Our finding provides a comprehensive view of proteome changes and their phosphorylation levels in goat muscle, involved in producing meats of different muscle parts. It also gives a better understanding of the regulation of protein on various biological processes that determine the final meat quality attributes.     

CO2浸渍发酵法研究进展

作为一种特殊的酿酒工艺,CO2浸渍法为酿制新型葡萄酒提供了新的思路。综述了CO2浸渍过程中化学成分和微生物群落的变化以及影响因素,并对CO2浸渍法的应用前景进行了展望。     

三光气替代光气合成双酚S/双酚A型聚碳酸酯

采用三光气替代光气合成双酚S/双酚A型聚碳酸酯,三光气无毒,无污染符,合环保要求.与普通以酚A型聚碳酸酯不同的是,双酚S的加入在很大程度上提高了聚碳酸酯的耐热性.实验将三光气溶于二氯甲烷溶液构成油相与双酚S/双酚A溶于氢氧化钠溶液构成的水相组成反应体系,通过实验合成高分子量的聚碳酸酯,对该反应的合成条件与产品的结构表征和性能进行进一步研究.