生物酶催化聚合的研究进展

酶催化聚合反应是近年来的研究热点之一,氧化还原酶是应用广泛的一类催化聚合酶。概括总结了近年来酶促聚合反应的研究进展,重点叙述了辣根过氧化物酶(HRP)、大豆过氧化物酶(SBP)和漆酶(laccase)的结构、催化机理以及它们在酶催化聚合中的应用概况。     

口腔过氧化物酶系统研究进展

口腔过氧化物酶系统由过氧化物酶、过氧化氢 ( H2 O2 )和可被氧化的底物组成 ,是口腔中重要的非特异性防御因子 ,该系统可通过过氧化氢 ( H2 O2 )及氧化产物维持或促进口腔有益菌的生长和繁殖 ,同时抑制或杀灭致龋菌、牙周可疑病原菌及致口腔粘膜病微生物 ,调节口腔菌群的种类和数量 ,在维持口腔微生态平衡和口腔健康中起着重要的作用 ,本文拟对口腔过氧化物酶系统的组成、生物学功能及其应用作一综述。1　口腔过氧化物酶系统的组成口腔过氧化物酶系统 ( peroxidase system,PS)包括三个组份 :过氧化物酶 ( peroxidase,PO)、过氧化氢 ( H…     

微体的概念及其发展

微体是一种细胞器,其种类主要包括过氧化物酶体、糖酵解酶体和乙醛酸循环体。本文主要介绍了微体的概念及其发展,乙醛酸循环体和过氧化物酶体之间的关系,过氧化物酶体、糖酵解酶体和乙醛酸循环体的功能。     

酵母过氧化物酶体的形成机制

过氧化物酶体是细胞中一种重要的细胞器.过氧化物酶体在细胞功能的发挥和人体健康方面有着重要作用.目前,以酵母过氧化物酶体为模型,研究过氧化物酶体的形成机制是研究热点.从过氧化物酶体起源、生成方式介绍最新研究进展,总结在酵母细胞中参与过氧化物酶体形成的必需基因(pex),及其编码Peroxin蛋白在过氧化物酶体形成过程中的...     

植物过氧化物酶超家族的分子结构

过氧化物酶广泛存在于生物中。基于序列相似性比较,可将真菌、细菌和植物来源的过氧化物酶归为一个超家族－植物过氧化物酶超家族。作者对近几年来植物过氧化物酶超家族的分子结构与功能研究进展,从过氧化物酶的辅基（血红素）微循环结构、过氧化物酶超家族的序列结构域,以及酶分子中底物结合位点和Ca^2＋结合位点的结构等方面作了简要评述。     

合酶与合成酶

合酶与合成酶是生化教学中经常提到的,同时也是比较容易混淆的两个概念。例如,对于三羧酸循环中催化乙酰ＣｏＡ与草酰乙酸反应生成柠檬酸的酶,国内教科书就出现了命名的混乱,有的书称为柠檬酸合酶,更多的书称为柠檬酸合成酶。此外,不少教科书把脂肪酸合酶、ＨＭＧＣｏＡ合酶、ＡＬＡ合酶及前列腺内过氧化物合酶误译成脂肪酸合成酶、ＨＭＧＣｏＡ合成酶、ＡＬＡ合成酶及前列腺内过氧化物合成酶等。可见,合酶与合成酶误用存在一定的普遍性。这种状况不仅使青年教师茫然,更使学生无所适从,实在有必要澄清。出现这种错误的可能原因一是名词的错…     

过氧化物酶体脂肪酸β氧化

除线粒体外,过氧化物酶体也是真核细胞脂肪酸β氧化分解的重要部位．过氧化物酶体β氧化过程包括氧化、加水、脱氢和硫解4步反应,主要参与极长链、支链脂肪酸等的分解．近年关于过氧化物酶体β氧化的研究活跃,在代谢途径及功能等方面有了新的认识,尤其在对相关代谢酶的研究中取得了较大进展．本文就过氧化物酶体β氧化相关进展作一综述．     

枸杞过氧化物酶的提取工艺优化及其酶学特性研究CSCD

枸杞为常用“药食同源”中药材,在加工、贮藏、运输等过程中易发生褐变,严重影响枸杞的外观和质量。前期研究发现枸杞中具有较高的过氧化物酶(peroxidase, POD)活性,而过氧化物酶在植物的酶促褐变中发挥着重要作用。为更好地控制枸杞酶促褐变的发生,本研究采用响应面法对枸杞过氧化物酶提取工艺进行优化,对枸杞过氧化物酶的性质进行了研究。结果显示枸杞过氧化物酶最佳提取工艺为料液比1∶3,浸提时间5 h,缓冲液pH为6.0,枸杞过氧化物酶活力为(5 148.59±50.00)U,与模型预测值接近,拟合性好,表明所得响应面模型可以很好地预测和分析枸杞过氧化物酶提取工艺条件。枸杞过氧化物酶最适温度为50℃,最适pH为6.0,金属离子Na~+、Ca~(2+)、K~+、Zn~(2+)、Cu~(2+)和柠檬酸对枸杞过氧化物酶起激活作用,抗坏血酸和亚硫酸能抑制枸杞过氧化物酶活性;该酶酶促反应动力学符合米氏方程,过氧化氢浓度一定时,酶对愈创木酚的K_m=21.52 mmol/L,V_(max)=115.47 U/mL;愈创木酚浓度一定时,酶对H_(2)O_(2)的K_m=1.41 mmol/L,V_(max)=148.81 U/mL。本研究可为后续枸杞加工过程中褐变的控制提供参考。     

芒果过氧化物酶活性的研究

从新鲜芒果中提取酶液,进行过氧化物酶活性的测定,结果表明：芒果酶提取液中过氧化物酶最适ＰＨ值为４．７５,米氏常数Ｋｍ值为３．２３×１０＾－３ｍｍｏｌＨ２Ｏ２／ｍＬ最大反应速度Ｖｍａｘ＝０．２４４Ｏ．Ｄ／ｍｉｎ。在７５℃下加热处理２０ｍｉｎ或８０℃下处理５ｍｉｎ,可使过氧化物酶完全失活。     

动物抗氧化系统中主要抗氧化酶基因的研究进展

抗氧化系统是机体清除体内多余的活性氧、保护自身免受氧化损伤的重要体系,其中超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶等起主要作用。本文将对动物抗氧化系统中,超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶基因的种类、分布、结构及表达进行综述。     

Concerning the question of individual constancy and individual specificity of three serum enzyme activities (serum cholinesterase EC 3.1.1.8, ceruloplasmin EC 1.10.3.2, and alkaline phosphatase EC 3.1.3.1)

Summary Several assays of the enzymatic activities of serum cholinesterase, ceruloplasmin and alkaline phosphatase of 30 healthy students during a 9 months period revealed quite constant enzyme levels for each subject. Further, it was observed that most of the subjects maintained a specific enzyme activity value and that the individual range of scatter was characteristic for each one of them.According to our studies it seems probable that quantitative enzyme assays in adults can also be rated as biochemical parameters of individuality.Supported by the Deutsche Forschungsgemeinschaft.     

Project-based learning in a collaborative group can enhance student skill and ability in the biochemical laboratory: a case study

ABSTRACT

Experimental courses for undergraduate students majoring in biochemistry or related subjects often do not provide students with systematic and research-based experiences. To help students develop abilities related to laboratory techniques, data analysis, and systematic thought in biology, we performed an exploratory program that employs project-based learning in collaborative groups. The participants (total of 18 students) organized themselves into groups of 2–4 students, and each group researched an enzyme that had not been described previously. The program began with a literature survey of enzyme and bioinformatics analysis. The students cloned the gene encoding the enzyme, purified the enzyme, and, finally, analyzed the enzyme’s catalytic characteristics. The students explained the catalytic mechanism, integrating their experimental data and other knowledge. An instructor provided support and training during the process to support effective teamwork and to cultivate a habit of independence that is believed to be useful for the students’ future careers. The assessment showed that the pilot program yielded an improvement in the participant’ laboratory skills, scientific presentation ability, and experimental design ability. These analyses indicated that the small-scale practice in this study provided benefits to the students and the methods may be popularized to a large extent.     

A simple laboratory experiment for teaching enzyme immobilization with urease and its application in blood urea estimation

An experiment is described in which students carry out urease purification, immobilization and its application in blood urea estimation. Urease from pigeonpea is partially purified using acetone fractionation and then immobilized on calcium alginate in the form of beads. The immobilized enzyme has a better shelf-life at 4°C than soluble enzyme. Various aspects of enzyme immobilization are discussed. Blood urea estimation is carried out with immobilized enzyme beads and the beads can be used repeatedly for this purpose making it an economical procedure compared to commercial kits.     

Organization of a molecular biology workshop in Tunisia

A five day laboratory course in Molecular Biology for PhD students is proposed. The aim of this program, which can be taught by a relatively small staff of experienced scientists, was to introduce basic experimental techniques which are of general use in various fields of biology and biomedicine. These include restriction enzyme purification, restriction mapping, polymerase chain reaction, cloning and DNA sequencing.     

On Some Logical Uncertainties in Genetics and their Significance

Amylose azure can be used as a chromogenic substrate for α-amylase in studying the effects of temperature and pH on enzyme action. This is a model system which students can use to measure the energy of activation using the Arrhenius plot. The temperature coefficient can also be determined. Further laboratory investigations can be designed to measure optimum pH under varying conditions and the effects of activators on the system.

This paper reviews a-amylase action with respect to temperature and pH. Further investigations are suggested.     

产业化案例辅助“酶工程”理论教学的探讨

介绍对生物技术和生物工程专业高年级学生开设的“酶工程”课程在教学内容、教学方法等方面的改革。采取产业化案例辅助理论教学的全新授课模式, 主要包括教材和授课内容体现工程特色、产业化案例辅助章节理论和整个课程体系教学、学生参与课堂互动教学等方面。通过教学改革, 收到较好的授课效果。     

The pH ruler: a Java applet for developing interactive exercises on acids and bases

In introductory biochemistry courses, it is often a struggle to teach the basic concepts of acid-base chemistry in a manner that is relevant to biological systems. To help students gain a more intuitive and visual understanding of abstract acid-base concepts, a simple graphical construct called the pH ruler Java applet was developed. The applet allows students to visualize the abundance of different protonation states of diprotic and triprotic amino acids at different pH values. Using the applet, the student can drag a widget on a slider bar to change the pH and observe in real time changes in the abundance of different ionization states of this amino acid. This tool provides a means for developing more complex inquiry-based, active-learning exercises to teach more advanced topics of biochemistry, such as protein purification, protein structure and enzyme mechanism.     

Progesterone in milk: a simple experiment illustrating the estrous cycle and enzyme immunoassay

Experiments designed for students in reproductive physiology are rare. Here, we describe a simple experiment concerning a physiological aspect of the reproductive system. Milk samples are obtained from cows in estrus, in midcycle, 21 days after insemination, and in gestation. With these samples, the gestation or estrous stage is determined according to the progesterone level in milk that is measured using enzyme immunoassay. This experiment can therefore be used to demonstrate assay techniques and to illustrate the variations in progesterone concentrations during an estrous cycle and gestation. This exercise should be given after the reproduction section of the animal physiology course so that students can apply their knowledge concerning hormonal profiles during an estrous cycle.     

A single protein research integrated advanced biochemistry laboratory course: design and general outline

An advanced biochemistry laboratory has been designed to focus on a detoxifying enzyme, glutathione-S-transferase, which is involved in the metabolism of polycyclic aromatic hydrocarbons (PAHs), pesticides, herbicides, and other electrophilic xenobiotic compounds. The enzyme is known to catalyze conjugation of glutathione to xenobiotics, which makes them water-soluble so that they can be easily discarded through further metabolism and excretion. About two-thirds of the laboratory course incorporates nine advanced biochemical techniques, all focused to analyze various chemical characteristics of the glutathione-S-transferase. The remaining third of the semester time students work on a project that involves application of all the newly acquired techniques to solve a biochemical problem that encompasses the same detoxifying enzyme.