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METABOLIZAM
UGLJIKOHIDRATA
METABOLIČKI PUTEVI
Shematski prikaz
katabolizma
Složeni metaboliti kao što su
ugljikohidrati, masti i proteini
razgrađuju se prvo do na
monomerne jedinice (većinom
glukozu, aminokiseline, masne
kiseline i glicerol), a zatim do
acetil-CoA koji ulazi u ciklus
limunske kiseline.
Lactose intolerance
Fate of Galactose and Fructose
BLOOD
fructose
fructose
glucose
galactose
glucose
galactose
LIVER
Absorption of glucose from the blood:
Facilitated diffusion
Glucose 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 je
povećana
Glucose Uptake by Muscles
and 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
Fruktokinaza
Glukoza-6-fosfataza
Fruktoza-1,6-bisfosfataza
Pregled ključnih reakcija i enzima
glikolize i glukoneogeneze
Piruvat
kinaza
Fosfoenol-piruvat karboksikinaza
Piruvat-karboksilaza
AEROBIC
ANAEROBIC
glucose
glucose
Minor Source
of ATP
ONLY Source of ATP
2 pyruvate
2 pyruvate
Minor Source
of ATP
2 acetyl CoA
TCA
Major Source
of ATP
2 lactate
Zašto
nastaje
laktat
Why
Lactate
is Formed?
glyceraldehyde-3-P
dehydrogenase
1,3-bisphosphoglycerate
glyceraldehyde-3-phosphate
ADP
ATP
3-phosphoglycerate
+
NAD
ETS
anaerobic
U Under
anaerobnim
(aerobic
conditions
uvjetima
ne the
djeluje
conditions
ETS
only)
respiratorni
lanac
doesn’t work
NADH + H+
2-phosphoglycerate
phosphoenolpyruvate
ADP
ATP
pyruvate
lactate
lactate dehydrogenase
Cori Cycle
3
2
4
1
Exercising muscles
also generate lactate
IV. CARBOHYDRATE METABOLISM
A. Digestion and absorption
B. Glycolysis
1. General characteristics
2. Individual reactions
3. Lactic dehydrogenase
4. Pyruvate oxidation
5. Energetics
Pyruvate Oxidation
H3C
O
pyruvate
dehydrogenase
O
H3C
COO
CoASH
NAD+
SCoA
+
CO2
NADH + H+
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 Pyruvate
Dehydrogenase
glucose
Stimulated by ADP
Inhibited by:
ATP, acetyl CoA and
excess fatty acids
pyruvate
CYTOSOL
ATP
pyruvate
carboxylase
pyruvate
CO2
pyruvate dehydrogenase
acetyl CoA
ADP + Pi
Stimulated by
Acetyl CoA
OAA
TCA
citrate
MITOCHONDRIA
Fatty Acids
Energetics of Glycolysis
AEROBIC
ANAEROBIC
glucose
glucose
2 ATP
- 2 ATP
2 NADH
ETS
2 ATP
6 ATP
4 ATP
4 ATP(SLP)
-2 ATP
NAD+
4 ATP 4 ATP
NADH
2 pyruvate
2 pyruvate
ETS
2 NADH
6 ATP
2 ATP NET
2 acetyl CoA
TCA
12 ATP x 2 =
24 ATP
NET 38 ATP
2 lactate
GLUKONEOGENEZA
SINTEZA GLUKOZE IZ
SPOJEVA KOJI NISU
UGLJIKOHIDRATI
2. Fosfoenol-piruvat
karboksikinaza
1. Piruvat
karboksilaza
2 KLJUČNA ENZIMA:
• PIRUVATKARBOKSILAZA
• PEP (FOSFOENOLPIRUVAT)
KARBOKSIKINAZA
Cori Cycle
3
2
4
1
Exercising muscles
also generate lactate
CIKLUS PENTOZA
FOSFATA
(PPP,CPF)
Overview of the Pentose
Phosphate Pathway
fatty acid synthesis
2 NADP+
glucose
2 NADPH
steroid synthesis
glutathione reduction
OXIDATIVE
PHASE
glucose-6- P
Oxidatively decarboxylates
glucose-6-P to ribulose-5-P ribulose-5- P
+ CO2
INTERCONVERSION
PHASE Converts ribulose-5-P back to
glyceraldehyde-3- P
glucose-6-P
METABOLIZAM
GLIKOGENA
1. GLIKOGENEZA
SINTEZA GLIKOGENA
(UTP)
2 Pi
GLIKOGENOLIZA
RAZGRADNJA GLIKOGENA
Glycogenolysis
H2 O
The Fate of Glucose-6-phosphate
Pi
glucose
Blood
(glucose-6-phosphatase)
phosphoglucomutase
Glucose-1- P
H2 O
LIVER
Glucose-6- P
MUSCLES
Glycolysis in
muscles for
energy
Summary of Glycogen
Metabolism
(immediately after a meal)
(2 to 3 hours following a meal)
*
*
Glucose-6-phosphatase
No glucose-6-phosphatase
Glucagon binds to receptors in the LIVER ONLY.
Epinephrine binds to receptors primarily in the
MUSCLES but also in LIVER.
GTP displaces
GDP on the a
subunit of the G
protein
GTP on the a
subunit is
hydrolyzed