CHEM237 Lecture Notes - Lecture 13: Alpha Helix, Dissociation Constant, Binding Constant

• School: University of Waterloo
• Department: Chemistry
• Course: CHEM237
• Professor: Dara Gilbert

Document Summary

Dissociation: kd = 1/ka = [p][l] / [pl] Fractional binding: y = [l] / [l] + kd. Partial oxygen: y = po2/po2 + kd. Cooperativity: y = (po2)n / (po2)n + kd. Thermodynamics of binding: dgo = -rtlnka = rtlnkd. A ligand binds to a protein at the binding site through non-covalent (non-reversible) bonds allowing for a reversible, transient equilibrium. Association equilibrium: ka = [pl]/[p][l] where large ka = tight binding < 0. 1nm (dgo <0, pl>p+l), on = how fast l finds p. Dissociation equilibrium: kd = 1/ka where large kd = loose binding > 10um (dgo >0, p+l >pl), off = how fast they detach. The [l] where half the binding sites are occupied. Y = [l] / [l] + kd. Binding curves: fraction of bound sites depends on [free l] and kd where l = known, independent (simple binding, no interaction between binding sites) Avidin and biotin: stable attractive complex due to very small kd.