酶的概念 Most Enzymes Are Proteins With the exception of a small group of catalytic RNA molecules, all enzymes are proteins. Their catalytic activity depends on the integrity of their native protein conformation. If an enzyme is denatured or dissociated into its subunits, catalytic activity is usually lost. If an enzyme is broken down into its component amino acids, its catalytic activity is always destroyed. Thus the primary secondary, tertiary, and quaternary structures of protein enzymes are essential to their catalytic activity
一、 酶的概念 With the exception of a small group of catalytic RNA molecules, all enzymes are proteins. Their catalytic activity depends on the integrity of their native protein conformation. If an enzyme is denatured or dissociated into its subunits, catalytic activity is usually lost. If an enzyme is broken down into its component amino acids, its catalytic activity is always destroyed. Thus the primary, secondary, tertiary, and quaternary structures of protein enzymes are essential to their catalytic activity. Most Enzymes Are Proteins
酶的概念 酶的概念酶是由生物细胞产生的以蛋白质为 主要成分的生物催化剂。 生物体内的反应是在很温和的条件(如温和的 温度、按近中性的pH)下进行的,而同样的反 应若在非生物条件下进行,则需要高温、高压、 强酸、强碱等剧烈的条件
一、 酶的概念 生物体内的反应是在很温和的条件（如温和的 温度、接近中性的pH）下进行的，而同样的反 应若在非生物条件下进行，则需要高温、高压、 强酸、强碱等剧烈的条件。 酶的概念—酶是由生物细胞产生的以蛋白质为 主要成分的生物催化剂
question?-- Keeping the Sweet Taste of Corn The sweet taste of freshly picked corn(maize)is due to the high level of sugar in the kernels. Store bought corn (several days after picking is not as sweet, because about 50%of the free sugar is converted to starch within one day of picking. To preserve the sweetness of fresh corn, the husked ears can be immersed in boiling water for a few minutes (<blanched )then cooled in cold water. Corn processed in this way and stored in a freezer maintains its sweetness. What is the biochemical basis for this procedure
The sweet taste of freshly picked corn (maize) is due to the high level of sugar in the kernels. Storebought corn (several days after picking) is not as sweet, because about 50% of the free sugar is converted to starch within one day of picking. To preserve the sweetness of fresh corn, the husked ears can be immersed in boiling water for a few minutes (“blanched”) then cooled in cold water. Corn processed in this way and stored in a freezer maintains its sweetness. What is the biochemical basis for this procedure? question?-- Keeping the Sweet Taste of Corn
酶的概念 但酶发挥其催化作用并不局限于活细胞内,在许 多情况下,细胞内产生的酶需分泌到细胞外或转移到 其它组织器官中发挥作用,如胰蛋白酶、脂酶、淀粉 酶等水解酶。把由细胞内产生并在细胞内发挥作用的 酶称为胞内酶,而将细胞內产生后分泌细胞外起作用 的酶叫胞外酶
一、 酶的概念 酶是但酶发挥其催化作用并不局限于活细胞内，在许 多情况下，细胞内产生的酶需分泌到细胞外或转移到 其它组织器官中发挥作用，如胰蛋白酶、脂酶、淀粉 酶等水解酶。把由细胞内产生并在细胞内发挥作用的 酶称为胞内酶，而将细胞内产生后分泌细胞外起作用 的酶叫胞外酶