ugljikohidrati

METABOLIZAM UGLJIKOHIDRATA

METABOLIČKI PUTEVI

Shematski prikazkatabolizma

Složeni metaboliti kao što suugljikohidrati, masti i proteinirazgrađuju se prvo do namonomerne jedinice (većinomglukozu, aminokiseline, masnekiseline i glicerol), a zatim doacetil-CoA koji ulazi u cikluslimunske kiseline.

Lactose intolerance

Fate of Galactose and Fructose

LIVER

fructose

galactose

fructose

galactose

glucose glucose

BLOOD

Absorption of glucose from the blood:

Facilitated diffusionGlucose Transporters (GLUT)

GLUT-1 through GLUT-5

TRANSPORT GLUKOZE U STANICU

1. OLAKŠANI TRANSPORT- uz transportere GLUT1-5, čiju aktivnost povećava INZULIN- npr. GLUT-4 je prisutan u adipoznom tkivu i skeletnim mišićima, a GLUT-1 u eritrocitima

- konc. Glu izvan stanice jepovećana

Glucose Uptake by Musclesand Fat Cells

TRANSPORT GLUKOZE U STANICU

2. KOTRANSPORT

-“protiv” koncentracijskog gradijenta- uz istovremeni transport Na+

-odvija se u intestinalnim epitelnim stanicama, te u bubrežnim tubulima

Metabolički putevi ugljikohidrata

• GLIKOLIZA• GLUKONEOGENEZA• CIKLUS PENZOZA FOSFATA

– oksidativni put– neoksidativni put

• GLIKOGENOLIZA• GLIKOGENEZA

GLIKOLIZA

Oksidativna razgradnja glukoze-6-fosfata do

piruvata

GLIKOLIZA

•AEROBNA GLIKOLIZA(glukoza-piruvat-acetil CoA-CLK-RL-ATP)

•ANAEROBNA GLIKOLIZA(glukoza-piruvat-laktat)

Heksokinaza

Pregled ključnih reakcija i enzima glikolize i glukoneogeneze

Glukoza-6-fosfataza

Fruktokinaza

Piruvat kinaza

Fruktoza-1,6-bisfosfataza

Fosfoenol-piruvat karboksikinaza

Piruvat-karboksilaza

AEROBIC ANAEROBIC

glucose

2 pyruvate

2 acetyl CoA

TCA

glucose

2 pyruvate 2 lactate

Minor Source of ATP

Minor Source of ATP

Major Source of ATP

ONLY Source of ATP

1. Traps glucose inside cells

2. Priming reaction:

Glucose + Pi Glucose-6-P + H2O +3300

ATP + H2O ADP + Pi -8000

Glucose + ATP Glucose-6-P + ADP -4700

3. Irreversible-4700

COO

C

CH3

O2 pyruvate

2 CoASH

2 CO2

2 NAD+

2 NADH + H+

H3C C S

O

CoA2

acetyl CoA

2 NADH + H+

2 NAD+

lactate dehydrogenase

pyruvate dehydrogenase

COO

CH

CH3

2 OH

lactate

1112

Why Lactate is Formed?

glyceraldehyde-3-phosphate

glyceraldehyde-3-P dehydrogenase

1,3-bisphosphoglycerate

ADP

ATP

3-phosphoglycerate

2-phosphoglycerate

phosphoenolpyruvate

pyruvate

ADP

ATP

NAD+

NADH + H+ETS(aerobic conditions only)

Under anaerobicconditions the ETSdoesn’t work

lactatelactate dehydrogenase

Zašto nastaje laktat

U anaerobnim uvjetima ne djeluje respiratorni lanac

Cori Cycle

Exercising musclesalso generate lactate

1

2

3

4

IV. CARBOHYDRATE METABOLISMA. Digestion and absorptionB. Glycolysis

1. General characteristics2. Individual reactions3. Lactic dehydrogenase4. Pyruvate oxidation5. Energetics

COO

C

CH3

O2 pyruvate

2 CoASH

2 CO2

2 NAD+

2 NADH + H+

H3C C S

O

CoA2

acetyl CoA

2 NADH + H+

2 NAD+

lactate dehydrogenase

pyruvate dehydrogenase

COO

CH

CH3

2 OH

lactate

1112

Pyruvate Oxidation

H3C COO

Opyruvatedehydrogenase

NAD+ NADH + H+

H3C SCoA

O

+ CO2

CoASH

Pyruvate Dehydrogenase is a multienzyme complex(like alpha ketoglutarate dehydrogenase)

Consists of 3 enzymes

Requires 5 coenzymes: TPP, coenzyme A,

lipoic acid, FAD and NAD+

Regulation of PyruvateDehydrogenase

pyruvate

pyruvate

glucose

CYTOSOL

MITOCHONDRIA

pyruvate dehydrogenase

acetyl CoA

OAA citrate

CO2

ATP

ADP + Pi

pyruvatecarboxylase

Fatty Acids

TCA

Stimulated by ADP

Inhibited by:

ATP, acetyl CoA andexcess fatty acids

Stimulated byAcetyl CoA

Energetics of GlycolysisAEROBIC ANAEROBIC

glucose

2 pyruvate

2 acetyl CoA

TCA

glucose

2 pyruvate 2 lactate

2 ATP

2 NADHETS

6 ATP

2 ATP- 2 ATP

2 NADHETS

6 ATP

4 ATP(SLP) 4 ATP

12 ATP x 2 = 24 ATP

-2 ATP

NADH

NAD+

4 ATP 4 ATP

NET 38 ATP

2 ATP NET

GLUKONEOGENEZA

SINTEZA GLUKOZE IZ SPOJEVA KOJI NISU UGLJIKOHIDRATI

Glucose

ATP

ADP

glucose-6-P

H2O

Pi

fructose-6-P

ATP

ADP H2O

Pi

ftuctose-1,6-bisphosphate

dihydroxyacetone-P

glyceraldehyde-3-P

2 Pi

2 Pi

2 1,3-bisphosphoglycerate

2 ATP

2 ADP

2 ATP

2 ADP

2 3-phosphoglycerate

2 2-phosphoglycerate

2 phosphoenolpyruvate

2 pyruvate

2 oxaloacetate

2 ADP

2 ATP

2 ATP

2 ADP + 2Pi

2 GTP

2 GDP

2 lactatelactate dehydrogenase

2 NAD+

2 NADH

1

2

3

4

1

2

3

4

Pyruvatecarboxylase

PEP carboxy- kinase

Fructose-1,6-bisphosphatase

Glucose-6-phosphatase

1. Piruvat karboksilaza

2. Fosfoenol-piruvat karboksikinaza

2 KLJUČNA ENZIMA:

•PIRUVATKARBOKSILAZA

•PEP (FOSFOENOLPIRUVAT) KARBOKSIKINAZA

Cori Cycle

Exercising musclesalso generate lactate

1

2

3

4

CIKLUS PENTOZA FOSFATA

(PPP,CPF)

Overview of the PentosePhosphate Pathway

glucose-6- P

glucose

OXIDATIVE PHASE

2 NADP+ 2 NADPH

fatty acid synthesis

steroid synthesis

glutathione reduction

ribulose-5- P + CO2

INTERCONVERSION PHASE

glyceraldehyde-3- P

Oxidatively decarboxylatesglucose-6-P to ribulose-5-P

Converts ribulose-5-P back toglucose-6-P

METABOLIZAM GLIKOGENA

1. GLIKOGENEZA

SINTEZA GLIKOGENA

(UTP)

2 Pi

GLIKOGENOLIZA

RAZGRADNJA GLIKOGENA

Glycogenolysis

H2O

The Fate of Glucose-6-phosphate

Glucose-1- P Glucose-6- Pphosphoglucomutase

H2O

Pi glucose Blood

Glycolysis inmuscles forenergy

LIVER

MUSCLES

(glucose-6-phosphatase)

Summary of GlycogenMetabolism

*

* Glucose-6-phosphatase

(immediately after a meal)

(2 to 3 hours following a meal)

No glucose-6-phosphatase

Glucagon binds to receptors in the LIVER ONLY.

Epinephrine binds to receptors primarily in theMUSCLES but also in LIVER.

GTP displacesGDP on the subunit of the Gprotein

GTP on the subunit ishydrolyzed