中职化学 第五章-酶 课件

第一章 第五章 酶 第一节 概述 第二节 酶的分子结构与功能 第三节 影响酶促反应的因素 第四节 酶与医学的关系 第一节 概述 第一节 一、 酶的相关概念 酶是由活细胞合成的、具有极高催化效率的一类蛋白质。 酶 酶促反应 酶所催化的化学反应称为酶促反应。 酶促反应中S为底物，P为产物，酶本身用E表示，所以酶促反应表示为 S P E Some functions of proteins. (a) The light produced by fireflies is the result of a reaction involving the protein luciferin and ATP, catalyzed by the enzyme luciferase (see Box 13–2). (b) Erythrocytes contain large amounts of the oxygen-transporting protein hemoglobin. (c) The protein keratin, formed by all vertebrates, is the chief structural component of hair, scales, horn, wool, nails, and feathers. The black rhinoceros is nearing extinction in the wild because of the belief prevalent in some parts of the world that a powder derived from its horn has aphrodisiac properties. In reality, the chemical properties of powdered rhinoceros horn are no different from those of pow-dered bovine hooves or human fingernails. 一、 酶的相关概念 底物(substrate, S)：酶作用的物质。 产物(product, P)：反应生成的物质。 酶活性：酶催化化学反应的能力。 酶失活：酶催化能力的丧失 Some functions of proteins. (a) The light produced by fireflies is the result of a reaction involving the protein luciferin and ATP, catalyzed by the enzyme luciferase (see Box 13–2). (b) Erythrocytes contain large amounts of the oxygen-transporting protein hemoglobin. (c) The protein keratin, formed by all vertebrates, is the chief structural component of hair, scales, horn, wool, nails, and feathers. The black rhinoceros is nearing extinction in the wild because of the belief prevalent in some parts of the world that a powder derived from its horn has aphrodisiac properties. In reality, the chemical properties of powdered rhinoceros horn are no different from those of pow-dered bovine hooves or human fingernails. 二、 酶学研究简史 公元前两千多年，我国已有酿酒记载。 一百余年前，Pasteur认为发酵是酵母细胞生命活动的结果。 1878年，Kühne首次提出Enzyme一词。 1897年，Eduard Buchner用不含细胞的酵母提取液，实现了发酵。 1926年，Sumner首次从刀豆中提纯出脲酶结晶 (deoxyribozyme)。 1982年，Cech首次发现RNA也具有酶的催化活性，提出核酶(ribozyme)的