Allosteric Regulation

MWC model — cooperativity, T/R state equilibrium, hemoglobin oxygen binding
T state
R state
MWC Model (Monod-Wyman-Changeux)
θ = α(1+α)³/(L(1+cα)⁴+(1+α)⁴)
α = [S]/K_R, L = [T]/[R]₀

Hill eq: θ = [O₂]ⁿ/(P₅₀ⁿ+[O₂]ⁿ)

Hemoglobin: 4 subunits, n≈2.8, P₅₀=26mmHg. High L → sigmoidal. c→1 → Michaelis-Menten.