Carbohydrates Metabolism Ppt PDF
7
1 Metabolism of Carbohydrates The Energy Metabolism of Glucose Entry of other Carbohydrates into Glycolysis Pyruvate Metabolism Biosynthesis of Carbohydrates Regulation of Carbohydrate Metabolism 2 Metabolism of carbohydrates 3 Carbohydrate metabolism 4 Energy metabolism of glucose Glycogen (animals) Starch (plants) Glucose Pyruvate Acetyl CoA Lactate Ethanol Ribose-5-phosphate + NADPH + H + Disaccharides ATP + NADH + H + catabolism anabolism phosphogluconate pathway glycolysis gluconeo- genesis aerobic anaerobic,muscles anaerobic,yeast 5 Glycolysis 6 First five reactions of glycolysis glucose glucose-6-P fructose-6-P fructose-1,6-bisP glyceraldehyde-3-P dihydroxyacetone-P ATP ADP ATP ADP 6 carbon stage Requires energy
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Transcript of Carbohydrates Metabolism Ppt PDF
1!
Metabolism of Carbohydrates
The Energy Metabolism of Glucose
Entry of other Carbohydrates into Glycolysis
Pyruvate Metabolism
Biosynthesis of Carbohydrates
Regulation of Carbohydrate Metabolism
2!
Metabolism of carbohydrates
3!
Carbohydrate metabolism
4!
Energy metabolism of glucose
Glycogen (animals) Starch (plants)
Glucose Pyruvate Acetyl CoA
Lactate
Ethanol
Ribose-5-phosphate + NADPH + H+
Disaccharides
ATP + NADH + H+
catabolism
anabolism
phosphogluconate pathway
glycolysis
gluconeo- genesis
aerobic
anaerobic,muscles
anaerobic,yeast
5!
Glycolysis
6!
First five reactions of glycolysis
glucose
glucose-6-P
fructose-6-P
fructose-1,6-bisP
glyceraldehyde-3-P dihydroxyacetone-P
ATP
ADP
ATP
ADP
6 carbon stage
Requires energy
7!
Reactions of glycolysis
1,3-bisphosphoglycerate
3-phosphoglycerate
2-bisphosphoglycerate
phosphoenolpyruvate
pyruvate
glyceraldehyde-3-P
ATP ADP
ATP ADP
NAD+
NADH + H+
H2O
Pi
3 carbon stage
Double this since two pyruvate
are made.
8!
Overall glycolysis
glucose 2 ADP + 2 PO4= + 2 NAD+!
2 pyruvate + 2 NADH + 2 H2O + 2 ATP!
10 enzymes!
9!
Entry of other carbohydrates into glycolysis
10!
Entry of other carbohydrates into glycolysis
maltase
invertase (bacteria)
sucrase (animals)
lactase
11!
Entry of other carbohydrates into glycolysis
12!
Entry of other carbohydrates into glycolysis
13!
Entry of other carbohydrates into glycolysis
Galactose
Galactose-1-phosphate
UDP-galactose UDP-glucose
Glucose-1-phosphate
Glucose-6-phosphate
galactokinase
galactose-1- phosphate uridyl
transferase UDP-galactose -4-epimerase
UDP-glucose pyrophosphorylase
Phospho- glucomutase
14!
Pyruvate metabolism
15!
Fermentation
16!
Lactate fermentation
17!
Alcohol fermentation
Used by anaerobic bacteria to obtain additional energy from glucose.
18!
Biosynthesis of carbohydrates
19!
Biosynthesis of carbohydrates
Skeletal muscles Glycogen
glucose-6-P exercise rest
glucose-6-P
pyruvate
lactate
Liver Glycogen
glucose-6-P
glucose-6-P
pyruvate
lactate
glucose
Muscles lack enzyme needed to convert pyruvate to glucose-6-P. Must be sent to liver.
Blood
20!
Gluconeogenesis
Oxaloacetate
Phosphoenolpyruvate
Pyruvate
Pyruvate Malate
Malate
Oxaloacetate
Lactate
Pyruvate
Pyruvate
Oxaloacetate
Phosphoenolpyruvate
Stage I
mit
och
on
dri
a
21!
Gluconeogenesis
Glycogen
Glucose
UDP-glucose
+ UDP
H O2Pi
ATP
H O2
Pi
Fructose-1,6-bisphosphate
Glyceraldehyde-3-phosphate
Phosphoenolpyruvate
3-Phosphoglycerate
2-Phosphoglycerate
Glucose-1-phosphate
Glucose-6-phosphate
Fructose-6-phosphate
ATP
Stage III
Stage II
22!
Gluconeogenesis
The process is sometimes called ‘reverse glycolysis’ but that is a misnomer.
Only seven of the ten steps in glycolysis are reversible. The three steps to be bypassed are:
1. glucose + ATP glucose-6-phosphate + ADP
3. fructose-6-phosphate + ATP fructose-1,6
-bisphosphate + ADP
10. PEP + ADP pyruvate + ATP
23!
Gluconeogenesis
24!
Gluconeogenesis
25!
Gluconeogenesis
26!
Gluconeogenesis
Fructose-6-phosphate
Fructose-1,6-bisphosphate
ATP
H2O
Pi
phospho- fructokinase
fructose-1,6- bisphosphatase
glu
co
ne
og
en
esi
s glyc
olysis
27!
Gluconeogenesis
glucose-6-phosphate + H2O glucose + Pi
glucose-6- phosphatase
28!
Synthesis of disaccharides and polysaccharides
29!
Activation of glucose and galactose
30!
Synthesis of UDP-galactose
31!
Synthesis of glycogen
Glucose, activated and tagged by attachment of UDP, is added to the nonreducing ends of an existing glycogen.
Glycogen synthase catalyzes the formation of a new ! (1 4) glycosidic linkage.
UDP-glucose + (glucose)n + H2O
(glucose)n+1 + UDP
32!
Synthesis of starch
Similar to glycogen formation except glucose is activated by ADP, not UDP.
Starch synthase catalyzes the addition of glucose to an existing starch molecule by formation of ! (1 4) glycosidic linkage.
ADP-glucose + (glucose)n
(glucose)n+1 + ADP
33!
Synthesis of lactose
This disaccharide is actively synthesized in the mammary glands of mammals.
It is produced by combining activated galactose with glucose using lactose synthase. A "(1 4) linkage results.
UDP-galactose + glucose
UDP + lactose
34!
Synthesis of sucrose
Sucrose is present in most fruits and vegetables. It is produced by a two step process.
UDP-glucose + fructose-6-phosphate
sucrose-6-phosphate + UDP sucrose + Pi
sucrose-6- phosphate synthase
phosphatase
H2O
35!
Synthesis of cellulose
Cellulose- major structural polysaccharide in cell walls of plants and some bacteria.
It’s synthetic route is similar to starch except a "(1 4) linkage is produced.
UDP-glucose or GDP-glucose + (glucose)n
UDP or GDP + (glucose)n+1
36!
Regulation of glycolysis
37!
Regulation of glycolysis
glucose
glucose 6-phosphate
fructose 6-phosphate
fructose 1,6-bisphosphate
phosphoenolpyruvate
pyruvate
feedback inhibition
