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Exergonic
- -reaction where ΔG is negative
- -reaction will proceed
- -energy level of reactants is higher than the products
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Endergonic
- -reaction where ΔG is positive
- -requires input of energy to proceed in forward direction
- -initial energy level of reactants is lower than that of products
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ΔG0'
-free energy change when calculated at 1M initial concentration, 1 ATM and at pH 7.0
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ΔG0=-R*T*ln(Keq)
- R is gas constant
- T is temp in Kelvin (273+celsius)
- Keq is equilibrium contant
- can also be written as ΔG0=-2.3*R*T*log(Keq)
- -when Keq=1 ΔG=0 (reaction at equilibrium)
- -when Keq<1 ΔG=+number, is an endergonic reaction favouring reverse reaction
- -when Keq>1 ΔG=-number, is an exergonic reaction, favours forward reaction
- -when coupling reactions ΔG values are additive, but Keq values are multiplicative
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Stability of ATP
- -ATP is very unstable because it has 4 negative charges
- -generally found in body bonded with magnesium, which relieves 2 negative charges
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High Energy Molecules
- -any molecule that gives higher than -25kJ/mol is considered high energy
- -4 compounds with higher ΔG values than ATP
- -phosphoenolpyruvate
- -1,3 bisphosphoglycerate
- -phosphocreatine
- -acetyl-CoA
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Prothetic Group
-covalently bonded to enzyme
-
Co-enzyme
-not covalently bonded to enzyme
-
NAD
- -nicotinamide bonded to adenine which is bonded through phosphodiester to another adenine
- -can be reduced to NADH+ H+
-
FAD
- -flavin adenine dinucleotide
- -has flavin bonded to ribose down to adenine monophosphate
-
ΔG0=-nFE0net
- -used to calculate ΔG based on electron affinity
- -n=number of electrons involved
- -F=faraday's number
- -E0'=net reduction potential
- -High E0' means HIGH affinity for e- low value means low affinity
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