Ligand binding intro

• Kₐ = [PL]/[P][L] = 1/conc. at equilibrium
• [P][L]/[PL] = $K_d$
• Larger $K_d$ means more reactant and less protein binding
• enzymes do not bind substrate so tightly
• Fraction bound = Θ = y = [PL]/[P]+[PL]
• $K_d$= [L] when Θ = 0.5, when protein sites are half-saturated