Metabolism of   carbohydrates
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Metabolism of carbohydrates. 1. summarize. 2. Digestion & absorption. • Hydrolyzed by enzyme. • Final products - glucose. • active absorptive process at small intestine. 3.blood sugar. • the sources & outlet. Catabolism (H 2 0,CO 2 ,ATP). Dietary carbohydrate.

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Metabolism of carbohydrates

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Metabolism of carbohydrates

Metabolism of carbohydrates

1. summarize


Metabolism of carbohydrates

2. Digestion & absorption

• Hydrolyzed by enzyme

• Final products - glucose

• active absorptive process

at small intestine


Metabolism of carbohydrates

3.blood sugar

• the sources & outlet


Metabolism of carbohydrates

Catabolism (H20,CO2,ATP)

Dietary carbohydrate

Liver ,muscle glycogen

Liver glycogen

Blood glucose

Other substrates

Glucogenesis (A.A,lactate,etc)

glycosuria


Metabolism of carbohydrates

• blood sugar concentration is

regulated by tissues,hormones

Decreasing blood sugar level:

hormone insulin


Metabolism of carbohydrates

elevating blood sugar level:

hormone

Glucagon,epinephrine,glucocorticoid, growth hormone


Metabolism of carbohydrates

Catabolism (H20,CO2,ATP)

Dietary carbohydrate

Liver ,muscle glycogen

Liver glycogen

Blood glucose

Other substrates

Glucogenesis (A.A,lactate,etc)

glycosuria


Metabolism of carbohydrates

Hyperglycosemia: >7.2mmol/L

Hypoglycosemia: <3.9mmol/L


Metabolism of carbohydrates

• The tolerance to carbohydrates

Tolerance test for glucose


Metabolism of carbohydrates

4. the catabolic pathway of

carbohydrates


Metabolism of carbohydrates

catabolic pathway of

carbohydrates

Aerobic

oxidation

anaerobic glycolysis

pentose pathway


Metabolism of carbohydrates

A. Anaerobic glycolysis

• concept

Glycolysis is the sequence of reactions that converts glucose into lactate with the concomitant production of ATP,under anaerobic conditions


Metabolism of carbohydrates

• the reaction site: cytosol

• basic process

(4 phases)


Metabolism of carbohydrates

1) phosphorylation of hexoses

G6P

G


Metabolism of carbohydrates

F6P

G6P


Metabolism of carbohydrates

FBP

F6P


Metabolism of carbohydrates

• the characteristics of

HK,PFK

• the changes of the energy

• the significance


Metabolism of carbohydrates

己糖激酶(HK)

a 二亚基的变构酶

b 催化不可逆反应,关键酶

ΔGo = -4.5 Kcal/mol

c 葡萄糖激酶是肝中存在的己糖激酶的同工酶


Metabolism of carbohydrates

高糖膳食后,肝中的 G G6P Gn 储存


Metabolism of carbohydrates

磷酸果糖激酶(PFK)

a 四亚基的变构酶

b 催化不可逆反应 关键酶

ΔGo = -3.4 Kcal/mol

c 酵解过程中的主要限速酶

★、 磷酸化酶 (phosphorylase)

a 催化反应, α-1,4 糖苷键

磷酸解

b 产物 G1P Gn-1


Metabolism of carbohydrates

2) Formation of glyceraldehyde-3-

phosphate (G3P) by cleavage and

isomerization

DAP

G3P

DAP


Metabolism of carbohydrates

3) Formation of pyruvate

a. dehydrogenation

BPG

G3P


Metabolism of carbohydrates

b. energy released

BPG

3PG


Metabolism of carbohydrates

c. transfer phosphoryl group

2PG

3PG


Metabolism of carbohydrates

d. dehydrate

2PG

PEP


Metabolism of carbohydrates

e. energy released

PEP


Metabolism of carbohydrates

4) reduction of pyruvate to

lactate


Metabolism of carbohydrates

• summarize

a. concept

b. the reaction site

c. basic process (4 phases)

d.key enzyme,limited enzyme

e. the changes of energy


Metabolism of carbohydrates

Consumption & generation of ATP

in glycolysis

ATP change per glucose

reaction

- 1

G-----------G6P

F6P--------FBP

-1

(2) BPG----(2) 3PG

+2

(2)PEP-------(2)pyruvate

+2

net +2


Metabolism of carbohydrates

f. characteristics

g. Physiologic role of glycolysis

• the control of glycolysis

a. enzymes

b. hormones

c. ATP/ADP


Metabolism of carbohydrates

LDH

CH3 - C- COOH CH3-CH-COOH

O OH

+ +

NADH+H+ NAD+


Metabolism of carbohydrates

B. Aerobic oxidation of glucose

• general


Metabolism of carbohydrates

lack of O2

O2

lactate

pyruvate

acetyl CoA

Citric acid cycle

Biological oxidation

CO2,H2O, energy


Metabolism of carbohydrates

• the reaction site

• basic process

(3 phases)


Metabolism of carbohydrates

  • glycolysis

  • (G----------pyruvate)

2) formation of acetylCoA

from pyruvate


Metabolism of carbohydrates

•Components of pyruvate dehydrogenase

complex


Metabolism of carbohydrates

3) Citric acid cycle

a. acetyl CoA entering Citric

acid cycle

(synthesis of citric acid )


Metabolism of carbohydrates

b. dehydrogenation & decarboxylation


Metabolism of carbohydrates

• In this stage produced:

2 molecules of CO2

2 pairs of NADH+H+

1 molecule of GTP


Metabolism of carbohydrates

c. Regenesis of oxaloacetate


Metabolism of carbohydrates

•the sources of oxaloacetate


Metabolism of carbohydrates

• In this stage produced:

1 pairs of FADH2

1 pairs of NADH+H+


Metabolism of carbohydrates

• summarize

a. concept

b. the reaction site

c. basic process (3 phases)

d. key enzyme

e. the changes of energy


Metabolism of carbohydrates

(32)


Metabolism of carbohydrates

NADH+H+

FADH2

ATP

GTP

CO2

H2O

Formation of pyruvate

2(1)

2或3

2(1)

2(1)

formation of acetyl CoA

acetyl

CoA enter TCA cycle

2(1)

2(1)

2(1)

2(1)

2(1)

2(1)

2(1)

2(1)

2(1)

2(1)


Metabolism of carbohydrates

Glucose+6O2 6CO2+6H2O = -2790kJ/mol

30.5KJ38/2790KJ=41%


Metabolism of carbohydrates

f. characteristics


Metabolism of carbohydrates

g. Physiologic role of aerobic

oxidation of glucose & TCA

cycle


Metabolism of carbohydrates

• the control of aerobic

oxidation of glucose & TCA

cycle

Pasteur effect

crabtree effect


Metabolism of carbohydrates

a. enzymes

b. hormones

c. ATP/ADP


Metabolism of carbohydrates

C .Pentose phosphate pathway

(hexose monophosphate shunt)

• general

• the reaction site


Metabolism of carbohydrates

• basic process

(2 phases)

a. Oxidation stage


Metabolism of carbohydrates

b. non oxidation stage


Metabolism of carbohydrates

C3

C6

C4

C7

C3

C6


Metabolism of carbohydrates

• Physiologic role of Pentose

phosphate pathway

a.providing NADPH+H+ for biosyntheses

b.Providing ribose 5-phosphate for nucleotide

lack of G6PDH (erythrocyte hemolytic

anemia)


Metabolism of carbohydrates

五、生理意义

①非供能,提供生物合成所需的原料

a、5-P核糖

b、还原型NADPH

⑴ 合成FA,类固醇激素,胆固醇

⑵ 维持体内一定量的GSH,保持RBC的完整性,保护SH酶的活性


Metabolism of carbohydrates

NADPH+H+ NADP+

G-S-S-G GSH

(oxidation) (deoxidized)

peroxides FA(unsaturated )

lysosome hydrolase

release

cell membrane hemolysis


Metabolism of carbohydrates

★ 遗传性GPDH缺乏症 蚕豆黄

c、加单氧酶体系供氢体

参与生物转化

d、WBC的杀菌作用,过氧化氢的

生成

2、3C,4C,5C,6C,7C糖的互变


Metabolism of carbohydrates

D. glycogenolysis

• concept

• the reaction site

• basic process


Metabolism of carbohydrates

E. glycogenesis

• concept

• the reaction site

• basic process


Metabolism of carbohydrates

  • The control of glycogenolysis

  • & glycogenesis


Metabolism of carbohydrates

G. gluconeogenesis

• concept

• the reaction site

• basic process


Metabolism of carbohydrates

HKPFK

G G6P G6F 1,6 2P-F(FBP)

3 PG BPG G3P

PK

PEP pyruvate


Metabolism of carbohydrates

ADP HK ATP

① G-6-P G

glucose-6-phosphatase

ADP PFK ATP

② 1,6-2P-F G6F

fructose I,6-biphosphatase


Metabolism of carbohydrates

3. Phosphoenelpyruvate is formed from

pyruvate by way of oxaloacetate

(bypass of carboxylation of pyruvate)

Key enzyme:

pyruvate carboxylase

PEP carboxykinase


Metabolism of carbohydrates

• the key enzyme

• Physiologic role of

gluconeogenesis


Metabolism of carbohydrates

  • In a long period of

  • starvation

  • Reuse of lactate: cori’s

  • cycle


Metabolism of carbohydrates

  • Promote the excretion

  • of H+ in kidney

  • # lactic acidosis


Metabolism of carbohydrates

H+ PEP carboxykinase

0xaloacetate PEP

Oxaloacetate , α-ketoglutarate oxatoacetate

α-ketoglutarate,

Glu

NH3 NH3+H+ NH4(excrete)

Gln


Metabolism of carbohydrates

• gluconeogenesis &

glycolysis are reciprocally

regulated


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