Chapter enzyme - 生物化学与分子生物学精品课 .pptVIP

Chapter 3. enzyme Composition Characteristics and mechanism Kinetics of enzyme-catalzed reaction Regulation Names and classes Enzyme and medicine Characteristics of competitive inhibition Inhibitor structure is similar to that of substrate Degree of inhibition is determined by their affinity and substrate concentration. Vmax is invariable, apparent Km increase. (2)non-competitive inhibition非竞争性抑制 Characteristics of non-competitive inhibition Inhibitor combine with essential groups out of active center, no competitive . Degree of inhibition is determined by the concentration of inhibitor. Vmax decrease, Km is invariable (3)uncompetitive inhibition反竞争性抑制 Characteristics of uncompetitive inhibition Inhibitor combine with enzyme-substrate complex only. Degree of inhibition is determined by concentration of both inhibitor and substrate. Vm decrease, Km decrease. Ⅵ. Influence of activator Activator激活剂：substance which change enzymes inactive into active state, or which increase enzyme activity, such as Mg2+, K+, Cl-. Essential activator Non-essential activator Ⅶ. Determination of enzyme activity ; enzyme activity unit The enzyme activity is determined by the reaction ratio. 1国际单位 IU = 在特定条件下，每分钟催化1μmol底物转化为产物所需要的酶量．Quantity of enzyme which can catalyze 1μmol substrate change into product at certain condition. 1催量kat＝在特定条件下，每秒钟催化1mol底物转化为产物所需要的酶量． 1IU = 16.67 ? 10-9 kat Section 4. the regulation of enzyme Regulated target: key enzyme Ways of regulation: Regulation of enzyme activity (fast). Regulation of enzyme quantity (slow). Ⅰ. Regulation of enzyme activity 1.Zymogen and activation of zymogen酶原与酶原激活 Zymogen: 有些酶在细胞内合成或刚分泌时，无催化活性，这种无催化活性的酶的前体． activation of zymogen： the process of inactive zymogen change into active enzyme, also the process of forming or exposing active center. 2. Allosteric regulation变构调节 效应剂 变构酶 调节亚基 催化亚基 3. Regulated by covalent modification of enzyme 磷酸化phosphorylation ? 脱磷酸化dephosphorylation 乙酰化acetylation ? 脱乙酰化产deacetylation 甲基化methylatio