《环境工程微生物学》课程教学课件（环境微生物学，讲稿）微生物的酶

第四章第一节微生物的酶

第四章 第一节 微生物的酶

微生物的酶酶的概述与分类；n 酶催化作用的特点;n 酶催化的化学本质;n 酶催化反应动力学;n 酶催化作用机理

微生物的酶 n 酶的概述与分类； n 酶催化作用的特点； n 酶催化的化学本质； n 酶催化反应动力学； n 酶催化作用机理

酶概述与分类Life is inconceivable withoutenzymes. Most of the thousands ofbiochemical reactions that sustainliving processeswouldatoccurimperceptible rateswwithouteenzymes.Enzymes are enormously powerfulcatalystseexhibitinghhighspecificity. Their catalyticactivities can be preciselyregulated

Life is inconceivable without enzymes. Most of the thousands of biochemical reactions that sustain living processes would occur at imperceptible rates without enzymes. Enzymes are enormously powerful catalysts exhibiting high specificity. Their catalytic activities can be precisely regulated. 酶概述与分类

概述：酶的研究历史酶的发现和提出：1897年，Buchner兄弟用不含细胞的酵母汁成功实现了发酵。提出发酵与活细胞无关，而与细胞液中的酶有关。1913年，Michaelis和Menten提出了酶促动力学原理一米氏学说。1926年，Sumner从刀豆种子中分离、纯化得到了脲酶结晶，首次证明酶是具有催化活性的蛋白质。1928年，Cech对四膜虫的研究中发现RNA具有催化作用

概述：酶的研究历史 n 酶的发现和提出：1897年，Buchner兄弟用 不含细胞的酵母汁成功实现了发酵。提出发酵 与活细胞无关，而与细胞液中的酶有关。 n 1913年，Michaelis和Menten提出了酶促动 力学原理—米氏学说。 n 1926年，Sumner从刀豆种子中分离、纯化得 到了脲酶结晶，首次证明酶是具有催化活性的 蛋白质。 n 1928年，Cech对四膜虫的研究中发现RNA具 有催化作用

The Nobel Prize in Chemistry 1907"for his biochemical researchesand his discovery of cell-freefermentation"Eduard BuchnerGermanyLandwirtschaftlicheHochschule (AgriculturalCollege) Berlin, Germany1860b.d.1917

The Nobel Prize in Chemistry 1907 "for his biochemical researches and his discovery of cell-free                fermentation" Eduard Buchner Germany Landwirtschaftliche Hochschule (Agricultural College) Berlin, Germany b. 1860 d. 1917

Urease crystals (OX 728)福CSumner, J. B. (1926) “The isolation andLcrystallization of theSenzyme urease" J. BiolOChem.69:435-441

Urease crystals ( X 728) Sumner, J. B. (1926) “ The isolation and crystallization of the enzyme urease” J. Biol. Chem. 69:435-441

The Nobel Prize in Chemistry 1946" for his"for their preparation of enzymes anddiscovery thatvirus proteins in a pure form"enzymes can becrystallized"James BatchellerWendell MeredithJohn Howard NorthropSumnerStanley1/2 of the prize1/4 of the prize1/4 of the prizeCornell UniversityRockefellerInstituteforMedicalRockefellerInstituteforMedicalIthaca, NY, USAResearchResearchPrinceton, NJ, USAPrinceton, NJ, USA1891-19871904-19711887-1955

The Nobel Prize in Chemistry 1946 “ for his discovery that enzymes can be crystallized" "for their preparation of enzymes and virus proteins in a pure form"                                              James Batcheller Sumner John Howard Northrop Wendell Meredith Stanley 1/2 of the prize 1/4 of the prize 1/4 of the prize Cornell University Ithaca, NY, USA Rockefeller Institute for Medical Research Princeton, NJ, USA Rockefeller Institute for Medical Research Princeton, NJ, USA 1887-1955 1891-1987 1904-1971

A chemical reaction is studied intwo aspects: thermodynamics andkineticsChemical thermodynamics deals with the questionof whether a chemical process can occur at all.Chemical kinetics deals with the rate of a chemicalhprocess.Many thermodynamically feasible reactions do notactually occur in the universe.The universe as we know it is as much controlled bythe laws of chemical kinetics as by the laws ofchemical thermodynamics

A chemical reaction is studied in two aspects: thermodynamics and kinetics n Chemical thermodynamics deals with the question of whether a chemical process can occur at all. n Chemical kinetics deals with the rate of a chemical process. n Many thermodynamically feasible reactions do not actually occur in the universe. n The universe as we know it is as much controlled by the laws of chemical kinetics as by the laws of chemical thermodynamics

How dose enzyme work? The answer to this questionrequires a review of the role of catalysts. Bydefinition a catalyst is a substance that enhancesthe rate of a chemical reaction but is notpermanently altered by the reaction. Catalystsperform this feat because they decrease theactivation energy required by a chemical reaction. Inother words, catalysts provide an alternativeUncatalyzedreaction pathway that requiriTransition state ()reactionA transition state occursAGtat the apex of bothuncat+reaction pathways in theAGtESHfigure. During anyPchemical reactionCatalyzedreactionreactants with sufficientReaction coordinateenergy will attaintransition stateconfiguration (a strained

How dose enzyme work? The answer to this question requires a review of the role of catalysts. By definition a catalyst is a substance that enhances the rate of a chemical reaction but is not permanently altered by the reaction. Catalysts perform this feat because they decrease the activation energy required by a chemical reaction. In other words, catalysts provide an alternative reaction pathway that requires less energy. Uncatalyzed reaction Catalyzed reaction A transition state occurs at the apex of both reaction pathways in the figure. During any chemical reaction reactants with sufficient energy will attain transition state configuration (a strained intermediate form)

EnzymescatalystsareCatalysts modifyttherrateoofaathey providereaction becausealterativeanreaction pathwaythatthan lessrequiresenergytheMostuncatalyzed reaction.proteins.enzymesare

Enzymes are catalysts. Catalysts modify the rate of a reaction because they provide an alterative reaction pathway that requires less energy than the uncatalyzed reaction. Most enzymes are proteins