Download Oxidation and reduction Metabolism consists of

2016-03-07
Metabolism consists of oxidation-reduction reactions
Course 2851 Principles of Metabolism
Metabolism and endocrinology programme, Karolinska Institutet
•
•
Catabolism = oxidation of carbon
+ 6 O2
Lecture 3
6 CO2
+ 6 H2O
Oxidation and reduction
Atom
H
P
C
S
N
O
Total number of electrons donated ( + ) or received ( – ) from bound atoms
Oxidation state = (# bonds shared with N, O) – (# bonds shared with H, P)
O
Highly reduced
“energy rich”
Anabolism = reduction of carbon
Highly oxidized
“energy poor”
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
State
-3
-2
-1
0*
0
+1
+2
+3
+4
More
electronegative
?
?—C—?
—
e–
(energy carrier,
e.g. NAD)
E
2.3
2.3
2.5
2.6
3.0
3.6
—
Department of Medicine, Solna
Center for Molecular Medicine
Karolinska Institutet
C
The ability of an atom to attract electrons
Electrons “prefer” more electronegative atoms – favorable
Oxidation state of carbon
•
Glucose
Roland Nilsson, Ph.D
Electronegativity
?
1
2016-03-07
Oxidation state of common metabolites
Oxidation state of common metabolites
Oxidation state of common metabolites
Highly reduced
“energy rich”
Highly reduced
“energy rich”
Highly reduced
“energy rich”
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
Highly oxidized
“energy poor”
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Choline
Methionine
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
Highly oxidized
“energy poor”
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Palmitate (saturated fat)
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Arachidonate (unsaturated fat)
Highly oxidized
“energy poor”
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Oxidation state of common metabolites
Oxidation state of common metabolites
Oxidation state of common metabolites
Highly reduced
“energy rich”
Highly reduced
“energy rich”
Highly reduced
“energy rich”
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
Highly oxidized
“energy poor”
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Glutamate
Histamine
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
Highly oxidized
“energy poor”
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Glucose
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Glyceraldehyde
Highly oxidized
“energy poor”
3
2016-03-07
Oxidation state of common metabolites
Oxidation state of common metabolites
Oxidation state of common metabolites
Highly reduced
“energy rich”
Highly reduced
“energy rich”
Highly reduced
“energy rich”
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
Highly oxidized
“energy poor”
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Acetoacetate
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
Highly oxidized
“energy poor”
State
-3
-2
-1
0*
0
+1
+2
+3
+4
Citrate
Functional group
—CH3
—CH2—
—CH=CH—
—CH(NH2) —
—CH(OH) —
—CH=O
—(C=O) —
—COOH
CO2
State
-3
-2
-1
0*
0
+1
+2
+3
+4
CO2
Highly oxidized
“energy poor”
4
2016-03-07
Can we predict what reactions will happen?
Redox perspective of metabolism
Electron carriers compartmentalize redox metabolism
Reduction
Pyruvate to lactate
Oxidizing a-ketoglutarate
+2
+4
0
+3
Saturated fat
Methyl groups (choline)
+2
Reduced substrate
Sugars
one-carbon
metabolism
Pyruvate
Lactate
+3 succinate
a-ketoglutarate
Unfavorable, proceeds to the left
Favorable, proceeds to the right
Nucleobases
glycolysis
Fatty acid
synthesis
Oxidation
Energy metabolism
Peptide bond
R
Amino acids
puryvate
+3
+3
R
R
Reduction
Biosynthesis
NADP
NADPH
Acetyl-CoA
Oxidized product
TCA
cycle
Amino acid 2
NAD / FAD
NADH / FADH2
Ketone bodies
R
+
Amino acid 1
Reduced product
Unsaturated fat
Oxidized substrate
Dipeptide
Carboxylates (citrate)
Borderline case!
But electroneg. of N = 3.0 < O = 3.6
CO2
Oxidation
5