Charateristics of enzymes 1. 2. 3. 4. too An enzyme is normally specific to ONE reaction that it catalyst. Enzymes are much more efficient than inorganic catalysts. Enzyme-catalyzed reactions only require mild conditions. Enzyme is sensitive to pH and temperature so is unstable under low or too high pH or too high temperature. Hydrolysis 水解 The chemical breakdown of a compound due to reaction with water Dehydration condensation 脱水脱核 A reaction in which two molecules combine to form a larger molecule, producing a small molecule such as H2O as a byproduct. 反应的原理：降低 activation energy Active site: specific region of an enzyme where a substrate binds and chemical reaction occurs. Substrate and naming of enzyme Substrate: the reactant presents at the beginning of the reaction Naming: enzymes are named according to its substrate Substrate+“ase“ • • • • • • • amylase––starch(amylose) protease––protein catalase––H2O2 (product: ) carbohydrase––carbohydrate lipase––lipid sucrase––sucrose maltase––maltose 例子：淀粉的消化过程 1. starch 经过口腔里的 amylose 作用，先变成 maltose；因为胃酸太强，所以 enzyme 无法存活，所以 starch 和 maltose 会接下来进入小肠，变成 glucose，epithelia 上 皮细胞会吸收 glucose，让其进入 blood vessel；由于血液里 glucose 不能太多，所 以 glucose 接下来会进入 liver，变成 glycogen，成为 energy source. 2. Undigested d food + water 进入大肠，在 rectum 直肠被 compressed 成为 solid. 在哪里发现 enzyme，那所在环境的温度就是这个 enzyme 的 optimum temperature Inhibition 在信号通路中也很常见