Biochem thermo

• tendency toward lowest energy state
• j/mol or cal/mol

• tendency to maximize randomness
• j/k

1 cal=4.18 j

rxn takes up heat

rxn becomes less ordered

rxn is unfavorable

• the total energy of a system remains constant
• energy cannot be created or destroyed

in all spontaneous processes total entropy of the universe increases

G=H-TS

• standard free energy change
• reactants and products at 1 M or 1 atm
• T=298 K

• biochemist convention
• rxn pH 7
• [H+]=10^-7

ΔG0=ΔG'0 + RTln [products]/[reactants]

ΔG'0=-RTlnKeq

• thermo-where is the eq. pointing
• kinetics-how fast is the equilibrium approached

• large ΔG'0
• ex: ATP(bond strain), PEP(Product stabilized by isomerization), Phospocreatin (product resonance stabilized), Acyl Phosphates (product ionization stabilized)
• release of Pi is favorable

thiol ester less stable than oxoester because of poor overlap between 3p e- orbital of sulfur and sp orbital of carbon

more - compounds can phosphorylate while less neg can be phosphorylated