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Just enough biochemistry to be dangerous??. http://www.detoxi-pad.com/. Just enough biochemistry to be dangerous??. http://www.tahitiannoni.com/united_states/english/retail/store/research/index.html. Chapter 15. Design of metabolism. http://www.chem.uwec.edu/Chem454_S08/MetabolicchartBig.pdf. - PowerPoint PPT Presentation
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Just enough biochemistry to be dangerous??
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Just enough biochemistry to be dangerous??
http://www.tahitiannoni.com/united_states/english/retail/store/research/index.html
Chapter 15
Design of metabolism
http://www.chem.uwec.edu/Chem454_S08/MetabolicchartBig.pdf
G, Free Energy, recall:G = ΔG° + RT ln[C]c [D]d
[A]a [B]baA + bB cC + dD
0 = ΔG° + RT ln[C]c [D]d
[A]a [B]b
G° = - RT ln[C]c [D]d
[A]a [B]b
G° = - RT ln Keq
For biochemical reactions, we define a different standard state for the concentration of H+standard state for [H+] = 10-7 M, pH = 7.0this modified standard state is given the symbol G°’
ATP
HHH
O
HO OH
N
N
N
N
NH2
-O-P-O-P-O-P-O-CH2
O
O-
O
O-
O
O-
H
ATP + H2O ADP + Pi + H+
K'eq =[ADP] [Pi] [H+]
[ATP] at pH 7.0 and 25°C
G°' = - (8.31 x 10-3 kJ mol-1) (298 K) ln 2.23 x 105
G°' = -30.5 kJ mol-1 = -7.29 kcal mol-1
the experimental value of K’eq = 2.23 x 105
ATP-Why?ATP + H2O ADP + Pi + H+
resonance
repulsion
BUT,it’s kinetically stable
Other “high energy compounds
"High energy" substance: a thermodynamically unstable substance whose hydrolysis or decomposition can be easily coupled to an unfavorable reaction. The arbitrary cut-off is ~-10kJ/mol. There is no such thing as a "high energy bond" per se.
Coupled ReactionsFree energies are additive; favorable rxns can drive unfavorable;e.g.sequential coupling
A B CK1 K2
K1
=
[ B ]
[ A ]
= 0 . 1
K2
=
[ C ]
[ B ]
= 100
Sequential coupling
acetylCoA Oxaloacetate
Citrate
+ Citryl CoA
CoA-SH+
Simultaneous coupling
A B CK3
+ D+
Example:Glucose to glucose-6-phosphate
glucose Pi glucose-6-phosphateK1
+
ATPK2
ADP Pi+
PEP + H2O Pyuvate+ Pi
ADP + H2OATP +Pi
G°' = -61.9 kJ mol-1
G°' = +30.5 kJ mol-1
Example: calculate G°’ for this reaction involving phosphoenolpyruvate (PEP) and decide whether or not it is spontaneous
use the following information from Table 14.1
Overall Coupling:Glucose to CO2 and H2O
C6H12O6
+
6O2
6CO2 6H2O
-2867
32ADP + 32Pi 32ATP
+
-1891
G°'(kJ mol-1)
C6H1 2O6 6 O2+ 3 2 AP + 3 2 Pi+
+6 CO2 6 H2O
3 2 ATP+
+976
Under aerobic conditions, glucose is oxidized to carbon dioxide and water
the efficiency of the energy conservation under aerobic conditions is approximately 34%
Metabolism concerns how you get from here to there!!
Metabolic strategies-Oxidation(burning of carbon containing compounds)
Substrate level phosphorylations
Ion gradients
Overall Process
Recurring Motifs in Metabolism “Activated” electron and functional group
carriers
Electron Carriers:
NAD+
H:-
Electron Carriers:
FAD
Typical Oxidation Reactions
“Carbon” carriers
Chemical Reaction “themes” in metabolism
Chemical Reaction “themes” in metabolism:Patterns
Factors Affecting Metabolic Rate
• Metabolism operates at a steady state.• Metabolites flow through the steady state
Factors Affecting Metabolic Rate
Factors Affecting Metabolic Rate
• Metabolites flow through the steady state
ATP
Factors Affecting Metabolic Rate
Factors Affecting Metabolic Rate
Factors Affecting Metabolic Flow or flux through pathways
• Amounts of enzymes
• Catalytic activity of enzymes
• Availability of substrates
ATP Balance affects many metabolic pathways
€
EnergyCh arge =[ATP]+ 1
2[ADP]
[ATP]+ [ADP]+ [AMP]
ATP Balance affects many metabolic pathways
CONTROL OF METABOLIC FLUX, J
€
S A BJ J
€
υF
€
υR
P
rate determiningstep
e.g. glucose pyruvate
CONTROL OF METABOLIC FLUX, J
e.g. Substrate Cycling:See glycolysis (F-6-P to F1,6-BP)