氨基酸极其重要衍生物的生物合成分析报告.ppt

Amino Acids and their Derivatives Biosynthesis 31.1 概论 31.2 脂肪族氨基酸的生物合成 31.3 芳香族氨基酸 及组氨酸的生物合成 31.4 氨基酸生物合成的调节 Plants and microorganisms can make all 20 amino acids and all other needed N metabolites. Mammals can make only 10 of the 20 amino acids. The others are classed as essential amino acids and must be obtained in the diet 研究氨基酸生酸生物合成过程多以微生物为材料，利用遗传突变技术。 EⅠ EⅡ E Ⅲ EⅣ EⅥ A B C D E F 氨基酸生物合成中的主要问题： 碳骨架的来源， 氮的进入 碳骨架： 代谢的主要干线-----柠檬酸循环、 糖 酵解、磷酸戊糖途径 氮： 主要来自于谷氨酸的转氨基作用。 生物体转化氨为有机化合物： Three major reactions in all cells: ?Carbamoyl-phosphate synthetase ?Glutamate dehydrogenase ?Glutamine synthetase 31.2 脂肪族氨基酸的生物合成 30.2.1 Biosynthesis of Glu family：Glu、Gln、Pro （Arg、Lys）a-ketoglutarate as precursor 30.2.2 Biosynthesis ofAsp family：Asp,Asn, Met, Thr（Lys, Leu） 30.2.3 Biosynthesis of Pyruvate family:：Ala, Val, Leu 30.2.4 Biosynthesis of Ser family: Ser, Gly, Cys The ?-Ketoglutarate Family Glu, Gln, Pro, Arg, and sometimes Lys The Aspartate FamilyAsp, Asn, Lys, Met, Thr, Ile The Pyruvate FamilyAla, Val and Leu 3-Phosphoglycerate FamilySer, Gly, Cys 31.3 芳香族氨基酸 及组氨酸的生物合成 31.3.1 Biosynthesis of Phe, Thy and Trp 31.4 Regulation of Amino Acid Biosynthesis 氨基酸的生物合成是受到严格调控的.机 制有多种： 1）? 调节酶活性 2）? 通过中间代谢物的调节 3）? 通过调节酶的生成量实现调节 最有效的是终端产物抑制 31.4.1 Inhibition of amino acid synthesis by the end product 简单的终端产物抑制 不同终端产物对共经合成途径的协同抑制 不同分支产物对多个同工酶的特殊抑制--- -酶的多重性抑制 ?连续产物抑制，及连续反馈抑制、逐步反馈抑制 Regulation of Amino Acid Biosynthesis Several feedback inhibition mechanisms are found to work in regulating amino acid biosynthesis. The first case of allosteric feedback inhibition was discovered in studying Ile biosynthesis in E. coli The enzyme catalyzing the first reaction (threonine dehydratase) is inhibited by the end product (Ile) in