Download LECT 08-Pyruvate

O2
O2
O2
O2
O2
METABOLISM OF
PYRUVATE
O2
O2
O2
Its time to get aerobic
Pyruvate Structure
Look for one NAD+ for each
glyceraldehyde-3-PO4 oxidized to pyruvate
Carboxyl group (acid)
Ketone group
(carbonyl)
a ketoacid
COO
-2
0
-OH
C=O
CH3
Methyl group
–2
+2
Net = –02
Oxidation of Carbon
–2
CH3
–2
C-OH
+2
H-C-OH
P
CH2OH
Glyceraldehyde
3-Phosphate
–2
–2
O
C
+2
C=O
O
+2
C=O
+2
CHO
O
Reactions of Pyruvate
(2) Add CO2
(1) Decarboxylate as CO2
H3C-C-COOO
(3) Reduce to alcohol (Lactate)
Each is catalyzed by a specific enzyme:
Remove
as CO2
(1) Pyruvate decarboxylase (anaerobic -yeast)
(1) Pyruvate dehydrogenase (aerobic-mitochondria)
(2) Pyruvate carboxylase (mitochondria)
(3) Lactate dehydrogenase (anaerobic-cytosol)
Decarboxylation Reactions
:C
O
O
O
+C
C
O
O
O
Two Types: non-oxidative and oxidative
Non-oxidative
CO2
H3C-C:COOO
NAD+
NADH
Oxidative
H3C-C:
O
H+ H3C-C:H
O
No change in
oxidation state
of carbonyl C
CO2
H3C-C+
O
H2 O
H3C-C-OH
O
Oxidized
carbonyl C
The Energy Story of Glycolysis
Overall ANAEROBIC (no O2)
Glucose + 2ADP + 2Pi
Yeast
Glucose + 2ADP + 2Pi
2 Lactate + 2ATP + 2H2O
2 Ethanol + 2CO2 +2ATP + 2H2O
Overall AEROBIC
Glucose + 2ADP + 2Pi + 2NAD+
2 Pyruvate + 2ATP + 2NADH + 2H+ + 2H2O
6 ATPs
Aerobic
C6H12O6 + 6O2
6CO2 + 6H2O
Anaerobic
CHO
H-C-OH
OH-C-H
H-C-OH
H-C-OH
CH2OH
D-Glucose
Go’= -2,840 kJ/mol
COOC=O
CH3
COO-
146
100 =
2,840
Energy used
C=O
CH3
2 Pyruvates
C6H12O6
2 C3H4O3
Glucose
2 Pyruvate
Go’= -146 kJ/mol
5.2%
Anaerobic
Lactate
Glycolysis
Glucose
Galactose
Fructose
Mannose
pyruvate
Fatty Acids
Acetyl-Coenzyme A
Aerobic
Amino Acids
Krebs Complex
Cycle
Pyruvate dehydrogenase
1Pyruvate
FADH2 dehydrogenase
Dihydrolipoyl transacetylase
Thiamin pyrophosphate
3 NADH
Lipoic acid
Dihydrolipoyl dehydrogenase
Oxidative
Coenzyme A
phosphorylation
FAD
NAD
O2
H2
O
+
CH2 N
N
CH3
N
CH2 CH2 O P O P O
CH3
Vitamin B-1
NH2
O
O
..
O
S
Carbanion
CH3 C : COO
+ CO2
O
Pyruvate
Thiamin pyrophosphate
COENZYME A
Acetyl-Coenzyme A
NH2
N
N
N
O O N
O
H
CH
3
HO
H
HS-CH2-CH2-N-C-CH2-CH2-N-C-C-C-CH2-O-P-O-P-O CH2
O
O
O
HO CH3
Pantothenate
O OH
B-vitamin
O P O
CH3C
Acetyl Group
O
Thioester bond
O
Adenosine-3’phosphate
Textbook p369
Dihydrolipoate
Long hydrocarbon chain
CH2
CH2
CH CH2 CH2 CH2 CH2 COO
HS
SH
6,8 Dithiooctonoate
(Reduced, gained 2 electrons)
CH2
CH2
S
CH CH2 CH2 CH2 CH2 COO
S
Disulfide bond
(Oxidized, lost 2 electrons)
Pyruvate Dehydrogenase Complex
Textbook p471-475
Acetyl-CoA
..
HS-CoA
C-CH3
O
..
CH3-C
O
..
CH3-C
NAD+
TPP
E1
E2
E3
FAD H2
..
NADH ..
OH
Pyruvate Dehydrogenase
Dihydrolipoyl
Transacetylase
Dihydrolipoyl
dehydrogenase
What about Yeast
Rule: Yeast do not synthesize lactate. Instead they make
acetaldehyde to regenerate NAD+ from NADH.
Rule: Acetaldehyde comes from pyruvate via a non-oxidative
decarboxylation.
Leavens bread
Makes wine sparkle
Pyruvate decarboxylase
CO2
CH3-C-COO
CH3-C :
CH3-C : H
pyruvate
O
O
O acetaldehyde
NADH NAD+
CH3-C-H
CH3CH2OH
ethanol
O
Alcohol dehydrogenase
Levels people
Makes AA sparkle