Bahan kuliah Biokimia dengan judul Metabolisme Karbohidrat

1. METABOLISME KARBOHIDRAT

5. Carbohydrate metabolism I

6. Carbohydrates
Carbohydrates
computing
composed of carbon, hydrogen and oxygen only
in the ratio C6H12O6
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd


7. Carbohydrates
• Contain carbon, hydrogen, and oxygen
• Their major function is to supply a source of
cellular food
• Examples:
– Monosaccharides or simple sugars
Figure 2.13a

8. Carbohydrates
• Disaccharides or double sugars
Figure 2.13b

9. Carbohydrates
• Polysaccharides or polymers of simple sugars
Figure 2.13c

10. Nutritionally important
disaccharides - 1
Nutritionally important disaccharides
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd
computing


11. α-1,4-binding
β-1,4-binding
Figuur 11. De α-1,4-binding en de β-1,4-binding die in polysacchariden voorkomen.

12. α-1,6-binding
Figuur 12. De α-1,6-binding zoals deze in amylopectine voorkomt.

13. Nutritionally important
disaccharides - 2
Nutritionally important disaccharides
computing
CH2OH
CH2OH
CH2OH
O
O
O
HO
OH
OH
OH
O
OH
OH
OH
maltose (glucosyl-glucose)
HO
O
OH
CH2
isomaltose
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd
O
OH
HO
OH
OH


14. Branched structure of starch
and glycogen
The branched structure of starch and glycogen
CH2OH
CH2OH
O
α1→6 links: branch points in
amylopectin and glycogen
O
OH
computing
OH
O
O
O
OH
OH
CH2OH
CH2
O
CH2OH
O
OH
O
OH
O
O
OH
OH
O
O
OH
CH2OH
OH
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd
O
OH
O
OH


15. Hydrolysis of starch
Hydrolysis by alpha-amylase formation of dextrins, computing
of starch by
in saliva and pancreatic juice results in
then:
amylase
glucose
maltose
isomaltose
CH2OH
CH2OH
O
α1→6 links: branch points in
amylopectin and glycogen
O
OH
OH
O
O
O
OH
OH
CH2OH
CH2
O
CH2OH
O
OH
O
OH
O
O
OH
OH
O
O
OH
CH2OH
OH
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd
O
OH
O
OH


16. The major types of non-starch
Major types ofpolysaccharide
non-starch
polysaccharides
computing
cellulose - glucose polymer linked β1→4
CH2OH
CH2OH
O
O
CH2OH
O
OH
O
CH2OH
O
OH
O
O
OH
O
OH
O
inulin - fructose polymer linked β2→1
O
OH
OH
OH
OH
CH2
HOCH2 O
OH
chitin - N-acetylglucosamine polymer linked β1→4
CH2OH
CH2OH
O
O
O
CH2OH
O
OH
O
CH2OH
O
OH
O
OH
HOCH2 O
O
OH
O
CH2
OH
OH
O
O
OH
HN
C
CH3
HN
O
C
HN
CH3
HN
C CH3
O
O
O
C CH3
OH
pectin - galacturonic acid polymer linked α1→4, partially methylated;
some glactose and/or arabinose branches
COOH
O
O
OH
OH
O
O
O
O
O
OH
O
OH
O
OH
CH2
HOCH2 O
COOH
CO CH3
COOH
CH2
HOCH2 O
OH
O
O
OH
OH
OH
OH
OH
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd


17. Glycaemic and noncomputing
Glycaemic index
The extent to which a test dose of a carbohydrate increases blood 1
glycaemic carbohydrates - glucose
compared with an equivalent amount of glucose
Glycaemic and non-glycaemic carbohydrates
Dietary starches can be classified as:
 rapidly digested (hence high glycaemic index)
 slowly digested (lower glycaemic index)
 not all digested in small intestine
 amylose is hydrolysed more slowly than amylopectin
 resistant starch (low glycaemic index)
 only hydrolysed to a limited extent in small intestine
 starch may be resistant because:
 it is crystalline and resistant to amylases
 it is enclosed in plant cell walls that are not digested
some resistant starch is fermented by bacteria in the large intestine
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd


19. Carbohydrates
• Serve as primary source of energy in the cell
• Central to all metabolic processes
Glucose
Cytosol - anaerobic
Hexokinase
Pentose
Phosphate
Shunt
Glucose-6-P
glycolysis
Pyruvate
Glc-1- phosphate
glycogen

20. cytosol
mitochondria
(aerobic)
Pyruvate
Aceytl CoA
FATTY ACIDS
Krebs
cycle
AMINO
ACIDS
Reducing
equivalents
Oxidative
Phosphorylation
(ATP)

21. insulin
IR
P
Protein Kinase B
(inactive)
Glycogen synthase kinase
(active)
P
Glycogen synthase
(inactive)
OH
P
Protein Kinase B
(active)
OH
synthase
P Glycogen(inactive) kinase
OH
Glycogen synthase
(active)
Glycogen formation

22. GLYCOGENOLYSIS
glycogen
glucose-6-phosphate
GLYCOGEN SYNTHESIS
glucose
( 6 carbons)
GLYCOLYSIS
GLUCONEOGENESIS
Overview of metabolism
computing
pyruvate
(3 carbons)
lactate
triacylglycerols
CO2
FATTY ACID SYNTHESIS
acetyl CoA
fatty acids
(2 carbons) FATTY ACID OXIDATION
ketones
KETOGENESIS
oxaloacetate
LIPASE
citrate
CITRIC ACID CYCLE
CO2
CO2
esentation copyright © 2002 David A Bender and some images copyright © 2002 Taylor & Francis Ltd


25. Glycolysis pathway

27. [Tri-carboxylic Acid (TCA) cycle]