生物化学教学课件：重要基酸及其衍生物的合成

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1、 Biosynthesis of Amino Acid and Physiologic Amines ？Humans can synthesize 10 of the 20 common amino acidsAlanineAsparagineAspartateCysteineGlutamateGlutamineGlycineProlineSerineTyrosineArginine*HistidineIsoleucineLeucineLysineMethioninePhenylalanineThreonineTryptophanValineEssential and Nonessential

2、 Amino Acids for Humans Essential Nonessential*Arg is essential in infants and growing children but not in adults. Most bacteria and plants can synthesize all 20 amino acids.AAs that an organism cannot synthesize under a given set of conditions are called “essential.” Those that can be synthesized i

3、n adequate amounts are “nonessential.”23Biosynthetic pathways for AAs:Six families corresponding to their metabolic precursorsa-Ketoglutarate Gives Rise to Glutamate, Glutamine,Proline, Arginine氨浓度很高时Oxidative deaminationCOOHCHNH2(CH2)2COOHL-Glu L-Glu DehydrogenaseNAD+NADH+H+COOHC NH(CH2)2COOHCOOHC(

4、CH2)2COOHH2ONH3O-ketoglutarateGlutamate Releases Its Amino Group as Ammonia in the Liver1 In hepatocytes mitochondria, 2 Glutamate undergoes oxidative deamination 3 Catalyzed by L-glutamate dehydrogenase4 Produces free ammonia5 Produces NADH 6 Required for Urea Cycle7 The enzyme is strictly regulate

5、dGlutamate and GlutamineGlutaminaseGlutamine synthetaseProline is a cyclized derivative of glutamate吡咯碄吡咯碄-5-羧酸羧酸还原酶还原酶吡咯吡咯-5-羧酸合成酶羧酸合成酶合成酶缺乏：合成酶缺乏：Too much pro. in blood白内障白内障智力迟钝智力迟钝皮肤过弹性皮肤过弹性脱氢酶缺乏：Too much pro，良性，良性，但是会诱发癫痫脱氢酶还原酶Urea cycleAAGluGluCarbamoylphosphateornithinecitrullinecitrullineArg

6、ininosuccinateornithinArginineOxaloacetateAAGluAspartate2ADP+Pi2ATP+CO2+NH3+H2O1cytosolmitochondrionUreaa-ketoglutarateH2N-C-O2345a-ketoglutaratea-ketoglutarateArginineIn liverArginine synthesis in kidney（no arginase)Serine, Glycine, Are Derived from 3-PhosphoglycerateCysteine Are Derived from 3-Pho

7、sphoglycerate （through serine）Mammals synthesize cysteine from homocysteine(高半胱氨酸）高半胱氨酸） and serine.Homocysteine，Methionine, S-adenosylmethionine,S-adenosylhomocysteine腺苷甲硫氨酸腺苷高半胱氨酸甲硫氨酸高半胱氨酸Three Nonessential and Six Essential Amino Acids Are Synthesized from Oxaloacetate and PyruvateEssential AAs:

8、Methionine, threonine, lysine, isoleucine, valine, leucine Nonessential AAs:AlanineAspartateAsparagineAsparagine is synthesized by amidation of aspartate, with glutamine donating the NH4 .Tyrosine formationfrom phenylalanine(Monooxygenase reaction)Tyrosine is considered a conditionally essential ami

9、no acid, or as nonessentialHumans can synthesize 10 of the 20 common amino acidsAlanineAsparagineAspartateCysteineGlutamateGlutamineGlycineProlineSerineTyrosineArginine*HistidineIsoleucineLeucineLysineMethioninePhenylalanineThreonineTryptophanValineEssential and Nonessential Amino Acids for Humans E

10、ssential Nonessential*Arg is essential in infants and growing children but not in adults. Most bacteria and plants can synthesize all 20 amino acids.AAs that an organism cannot synthesize under a given set of conditions are called “essential.” Those that can be synthesized in adequate amounts are “n

11、onessential.”23谷氨酸族谷氨酸族天冬氨天冬氨酸族酸族丙氨丙氨酸族酸族丝氨丝氨酸族酸族His 和和芳香族芳香族Molecules Derived from Amino AcidsvBiological Amines Are Products of Amino Acid Decarboxylation vCreatine，glutathioneAmino acid decarboxylationCOOCH3NHR_+(biotin)CO2NH3CH2R+Biological amineamino aciddecarboxyl. productexamples of functions

12、aspartic acid alaninecoenzyme Acysteinecysteaminecoenzyme Adihydroxy-phenylalaninedopamineneuro-transmitterglutamic acidg g aminobutyric acidneuro-transmitterhistidinehistaminemediator in allergic reactionslysinecadaverinecorpse venomornithineputrescinepolyamine metabolismserineethanolaminephospholi

13、pidsthreonineaminopropanolvitamine B12tyrosinetyramineuterus contractiontryptophanetryptamineprobably hormon actionhydroxy-tryptophaneSerotonine血清素neuro-transmitterFormation of biological aminesMetablism derivates, parkinson, albinism褪黑激素血清素脑中的神经递质，动脉和支气管平滑肌收缩诱导睡眠，晚间合成诱导睡眠，晚间合成松果体，视网膜松果体，视网膜Creatine

14、 kinasemitochondrialCreatine kinasecytosoliccreatineCreatine phosphateCreatine（肌酸）（肌酸）Phosphocreatine, important energy buffer in skeletal muscle.Creatine is synthesized from glycine and arginine; Methionine acts as methyl group donor.Phosphate CreatineArgGlycineornithinePhosphate CreatineCreatineMe

15、tGlutathione还原剂，还原剂，酶辅助因子，酶辅助因子，氨基酸跨膜运输，氨基酸跨膜运输，蛋白质二硫键重排，蛋白质二硫键重排，维持红细胞膜的稳定性（抗过氧化物）维持红细胞膜的稳定性（抗过氧化物）儿茶酚儿茶酚 儿茶酚和男性、女性糖代谢的差异男性、女性糖代谢的差异女性长时间运动，女性长时间运动，血糖从未降到基础以下血糖从未降到基础以下而且往往高于运动前水平而且往往高于运动前水平女性运动中产生儿茶酚：促进肝糖原和肌糖原分解 脂肪动员和利用能力强 糖异生女性三羧酸循环的酶活力比男性强Study of the biosynthesis of amino acid E E E E E A B C D E FQuestions1 根据氨基酸合成中的碳骨架来源，氨基酸合成分成主要有哪几族？2 什么是必需氨基酸和非必需氨基酸？掌握几种主要非必需氨基酸的合成的前体。3 重要的氨基酸衍生生物活性物质的前体的作用和来源。