华科同济医学院生物化学课件氨基酸代谢-3

CHAPTER 7

第 七 章氨基酸代谢Metabolism of Amino Acids

Section 5Metabolism of Inpidual Amino Acids个别氨基酸的代谢

目录

一、Decarboxylation of amino acidsgenerates special amines氨基酸的脱羧基作用产生特殊的胺类化合物

Decarboxylation (脱羧基作用)R H C NH2

COOH

Amino acids氨基酸

( 氨基酸脱羧酶) Amino acid decarboxylase RCH2NH2 Phosphopyridoxal Amines (磷酸吡哆醛) 胺类

+ CO2

Coenzyme pyridoxal phosphate磷酸吡哆醛

目录

Monoamine oxidase Amines Aldehyde 胺类 醛类

Carboxlic acids 羧酸类

目录

(一) γ-aminobutyric acid, GABA (γ-氨基丁酸) is generatedfrom glutamate catalyzed by glutamate decarboxylase谷氨酸经谷氨酸脱羧酶催化生成γ-氨基丁酸(GABA)

COOH

L- glutamate

(CH2)2CHNH2

decarboxylaseL- 谷氨酸脱羧酶

COOH (CH2)2 CH2NH2

CO2

COOH

L-glutamate

L-谷氨酸

GABA

γ-氨基丁酸

GABA is a kind of inhibitive neurotransmitter which has inhibitive function to central nerve system. GABA是抑制性神经递质，对中枢神经有抑制作用。目录

(二)Decarboxlation of histidine catalyzed by histidine decarboxlase generates histamine 组氨酸经组氨酸脱羧酶催化生成组胺CH2CHCOOH HN N NH2Histidine decarboxlase 组氨酸脱羧酶 组氨酸脱羧酶

CH2CH2NH2 HN N

CO2

L-histidineL-组氨酸

Histamine组胺

Histamine is an intensive vasodilator which can increase the permeability of blood capillary and stimulate the secretion of

pepsinogen and gastric acid.组胺是强烈的血管舒张剂，可增加毛细血管的通透性，还可刺激胃蛋白酶原及胃酸 目录 的分泌。

(三)5-hydroxytryptamine, 5-HT (5-羟色胺 ) is generated from tryptophane via 5-hydroxytryptophan 色氨酸经5-羟色胺酸生成5-羟色胺5-羟色氨酸脱羧酶 5-hydroxytryptophan decarboxylase HOCH2CHCOOHNH2 CO2

CH2CHCOOH NH2

HO

CH2CH2NH2

Tryptophan hydroxylase Tryptophane 色氨酸羟化酶

5-hydroxytryptophan5-羟色氨酸

色氨酸

5-HT5-羟色胺

5-HT serving as neurotransmitter has inhibitive function in brain , and it also plays a role in contraction of blood vassele

in peripheral tissues.5-HT在脑内作为神经递质起抑制作用；在外周组织有收缩血管的作用。目录

(四)Some amino acids can produce polyamines through decarboxylation某些氨基酸的脱羧基作用可产生多胺类 丙 Propylamine 鸟氨酸 胺 transferase 转 SAM decarboxylase Decarboxylated S-adenosyl 移 SAM methionine (SAM ) 酶 CO2 脱羧基SAM SAM脱羧酶 5'-甲基-硫-腺苷 S-腺苷甲硫氨酸 5'-methyl-S-adenosine Propylamine decarboxylase Spermidine (精脒 ) Spermine (精胺 ) (丙胺转移酶) Ornithine Onithine decarboxylase Putrescine (鸟氨酸脱羧酶) CO2 腐胺

Polyamines are important substances responsible for regulation of cell growth. 多胺是调节细胞生长的重要物质。目录

二、The catablism of some amin

o acids can

generate --- One carbon unit ( 一碳单位)某些氨基酸在分解代谢中产生一碳单位

(一)Tetrahydrofolic acid acts as a carrier of onecarbon unit and participates the metablism

of one carbon unit四氢叶酸作为一碳单位的运载体参与一碳单位代谢

Concept of one carbon unit

一碳单位的定义

The groups containing one carbon atom generated from the catabolism of some amino acids is called one

carbon unit (一碳单位).某些氨基酸在分解代谢过程中产生的含有一个碳原子的基团，称为 一碳单位(one carbon unit)。目录

Types of one carbon unitmethyl (甲基 )methylene (甲烯基 ) methenyl (甲炔基 )

一碳单位的种类

-CH3-CH2-CH=

formyl (甲酰基 )formimino (亚胺甲基 )

-CHO-CH=NH

目录

FH4 is a carrier of one carbon unit 维生素B11(叶酸,Folic Acid)结构

FH4 携带一碳单位的形式

目录

Structure of tetrahydrofolic acid

四氢叶酸的结构

叶酸在5、6、7、8位加上四个氢，生成四氢叶酸 (FH4),四氢叶酸是一碳单位的载体，传递一碳单 位。 它在核酸和蛋白质的代谢中具有重要意义。

5,6,7,8- tetrahydrofolic acid (FH4)目录

Generation of FH4FH2还原酶 FH2 reductaseNADP+

FH4的生成

F

FH2

FH2还原酶 FH2 reductase

FH4

NADPH+H+

NADPH+H+

NADP+

目录

FH4 is a carrier of one carbon unit FH4 携带一碳单位的形式 (One carbon unit usually links to the N5 or N10 position of FH4)一碳单位通常是结合在FH4分子的N5、N10位上 N5—CH3—FH4

N5,N10—CH2—FH4N5,N10=CH—FH4 N10—CHO—FH4 N5—CH=NH—FH4

目录

(二) Different one carbon units generated from amino acids can undergo interconversion由氨基酸产生的一碳单位可相互转变

The one carbon unit is generated from the catabolism of serine、glysine and histidine.一碳单位主要来源于丝氨酸、甘氨酸、组氨酸及色氨酸的分解代谢

Serine丝氨酸

N5, N10—CH2—FH4 N5, N10—CH2—FH4 N5—CH=NH—FH4

Glycine甘氨酸

Histidine组氨酸

Tryptophan色氨酸

N10—CHO—FH4

一碳单位的来源：肝胆阻塞死 (甘氨酸、蛋氨酸、组氨酸、色氨酸、丝氨酸)目录

The interconversion of different one carbon units一碳单位的互相转变

N10—CHO—FH4H+

H2O

NH3

N5, N10=CH—FH4NADPH+H+

N5—CH=NH—FH4

NADP+

N5, N10—CH2—FH4NADH+H+ NAD+

N5—CH3—FH4目录