中南大学 生物化学 考研课件 ch14 酶动力学 enzyme kinetics06.ppt

1、Biochemistry,For Speciality of Biotechnology or Bioengineering at CSU Mr. XIA Jinlan,Chapter 14 Enzyme kinetics,Introduction to enzymes 酶（学）导论 Factors affecting enzyme activity 影响酶活性的因素 Enzyme assays Enzyme kinetics and inhibition 酶动力学和抑制作用,Introduction to enzymes 酶（学）导论,The features of enzymes 酶的特征

2、 Some terms of enzyme 酶的几种术语 Classes of enzymes 酶的种类 Enzyme Nomenclature 酶的命名法 Traditional nomenclature 传统命名法 Systematic nomenclature 系统命名法 Expression of enzyme activity 酶活性的表示 Components of enzyme 酶的成分 Cofactors 辅助因子,Powerful Catalytic power 强的催化力 Increase reaction rate up to 1016 fold Make reactio

3、n taken place under relatively mild conditions of temperature and pH High specificity 高的特异性 To the substrates that they act on and the products they form Enzyme activity can be regulated 酶活性可以被调控 Basically are proteins, except few ribozymes 除了少量的核酶外,基本上是蛋白质,Enzymes have four basic features酶的四个基本特征,S

4、ome terms of enzymes 酶的几种术语,Proteoenzyme蛋白酶 Ribozyme核酶 Abzyme 抗体酶 Holoenzyme全酶 Apoenzyme脱辅酶 Multimeric enzyme多聚合体酶(多亚基酶),Enzymes are classified into six classes based on the type of reaction catalyzed基于催化反应的类型,酶可分为六种类型,Oxidoreductases 氧化还原酶 Transfer of electrons 电子的转移 Transferases 转化(或转移)酶 Transfer

5、of functional groups 分子间功能基团的转移 Hydrolases 水解酶 Hydrolysis reactions 水解反应 Lyases 裂解酶 Cleavage of C-C, C-O, C-N etc., often forming a double bond C-C, C-O, C-N键的裂解,并通常形成双键的反应 Isomerases 异构酶 Transfer of groups within a molecule 分子内基团的转移 Ligases (or synthases) 链接酶(或合成酶) Bond formation coupled to ATP hyd

6、rolysis伴随ATP水解的键合,Enzymes are classified into six classes based on the type of reaction catalyzed,Traditional Nomenclature of enzymes,Systematic nomenclature: Each enzyme is uniquely identified by a four-digit classification number,Enzyme commission (EC) number: Four-digit classification number What

7、 do these numbers signify?,Trypsin EC 3.4.21.4 Chymotrypsin EC 3.4.21.1 Elastase EC 3.4.21.36,Expression of enzyme activity 酶活性的表示,Initial rate (V0) of the reaction mmol of substrate transformed per minute 每分钟转化底物的微摩尔数 V0: X mmol.min-1 Enzyme unit 酶的单位, SI unit The amount that catalyzes the formatio

8、n of one mmol of product per minute 每分钟催化1mmol产物的形成所需的酶量 U: mmol.min-1 Katal , SI unit Amount of enzyme catalyzing the conversion of one mole of substrate to product per second每秒钟催化转化1摩尔底物所需的酶量 Katal: mol.s-1,Expression of enzyme activity酶活性的表示,1,1,Some expressions of the components of an enzyme酶的成分

9、的几种表示方式,Enzyme 酶 Protein part + Cofactors (Non-protein part) (蛋白部分+辅助因子(非蛋白部分) Holoenzyme全酶 Apoenzyme + Prosthetic group (脱辅基酶+辅基),Cofactors 辅助因子,Inorganic Inorganic ion(s) 无机离子 Fe2+, Zn2+, Cu2+, etc. Inorganic cluster(s) 无机簇 Fe-S cluster, Mn-O complex,etc Organic Coenzyme 辅酶 Which loosely bind to t

10、heir enzymes Prosthetic group 辅基 Which tightly bind to their enzymes,The important coenzymes and prosthetic groups 重要的辅酶和辅基,Coenzymes 辅酶 Coenzyme A (CoA) NAD(H), NADP(H) Nicotinamide adenine dinucleotide 烟酰胺腺嘌呤二核苷酸 Nicotinamide adenine dinucleotide phosphate Prosthetic groups 辅基 FAD(H2), FMN(H2)* Fl

11、avin adenine dinucleotide 黄素腺嘌呤二核苷酸 Flavin mononucleotide 黄素单核苷酸 Biotin 生物素 Heme 血红素,* FAD and FMN in most cases are prosthetic groups binding to flavin proteins,Water soluble vitamins (Vitamin B) Thiamine (B1) 硫胺素 In Coenzymes：thiamine pyrophosphate 存在于硫胺焦磷酸辅酶中 Riboflavin (核黄素B2) As prosthetic grou

12、p flavin protein: FAD and FMN Nicotinic acid (niacin烟碱酸) In Coenzymes: NAD and NADP Pantothenic acid (泛酸） In Coenzyme A Biotin (生物素） In prosthetic group: Biocytin生物胞素 Lipid soluble vitamins (Vitamin A, D, E, K) Vitamin A Retinal 视网膜素：vision, growth and reproduction,Most coenzymes are derived from vi

13、tamins大多数辅酶源于维生素,Some common coenzymes, their vitamin precursors and deficiency diseases,Coenzyme A,Transfer of acetyl group,NAD+, NADP+,Coenzyme of Dehydrogenases,NAD+, NADP+,General reaction,FAD, FMN,Fig. 18.21, p591,Isoalloxazine 异咯嗪,Flavin mononucleotide, FMN,Flavin adenine dinucleotide, FAD,Rib

14、oflavin,AMP,Ribitol 核醣醇,FAD, FMN,Chemical structure of biotin,Chapter 14 Enzyme kinetics,Introduction to enzymes 酶（学）导论 Factors affecting enzyme activity 影响酶活性的因素 Enzyme assays Enzyme kinetics and inhibition 酶动力学和抑制作用,Cofactors 辅助因子 (SEE the last section) pH Temperature Substrate concentration 底物浓度

15、Product concentration,Factors affecting enzyme activity,Chapter 14 Enzymes,Effect of pH,Effect of temperature,50 C, decrease due to denaturation of enzyme,Typically,Enzyme assays 酶的检测,Two most convenient ways Detg. the rate of appearance of product 测定产物形成的速率 Detg. the rate of disappearance of substr

16、ate 测定反应物减少的速率 A linked enzyme assay way 酶联检测法 First enzyme reaction + second enzyme reaction,Measurements 测定 Spectrophotometry 分光光度法 Enzyme electrode 酶电极法,LDH: lactate dehydrogenase 乳酸脱氢酶,葡萄糖氧化酶,过氧化氢氧化酶,葡萄糖酸,Chapter 14 Enzyme kinetics,Introduction to enzymes 酶（学）导论 Factors affecting enzyme activity

17、 影响酶活性的因素 Enzyme assays Enzyme kinetics and inhibition 酶动力学和抑制作用,Enzyme kinetics and inhibition (酶动力学和抑制作用),Catalytic mechanism 催化机制 Enzyme kinetics 酶动力学 Michaelis-Menten model Enzyme inhibition 酶的抑制 Reversible inhibition 可逆抑制 Nonreversible inhibition 非可逆抑制,Enzymes catalyze chemical reaction through

18、 lowering its activation energy,G0: not thermodynamically favorable,Activation Energy Rate Constant of Reaction Gk,Arrhenius equation,G,k,Questions (self study) What does dynamic equilibrium mean? Enzymes can accelerate the attainment of the equilibrium position, can it change this position? Whats r

19、ole of active site of an enzyme? By which forces the substrate binds to the active site of an enzyme?,Chemical equilibrium: (self study),Michaelis-Menten model,Hyperbolic curve双曲线,Double reciprocal or lineweaver-Burk plot,Measurement and calculation of V0,Enzyme inhibition 酶的抑制,Inhibition 抑制的定义 A ph

20、enomenon of lowering enzymes catalytic rate. Inhibitor 抑制剂 Any molecule which acts directly on an enzyme to lower its catalytic rate Two main types of inhibitions Irreversible 非可逆抑制(抑制) Reversible 可逆(抑制) Competitive 竞争性 Noncompetitive 非竞争性 Mixed noncompetitive inhibition 混合型非竞争性,Irreversible inhibition by covalent binding between I and E,Residues to be bound Susceptible amino acid residues near the active site Ser, with OH group Cys, with SH group Principle Cha