Ligand binding Flashcards
Types of ligand binding (4)
single binding site
multiple identical independent binding site
multiple non-identical independent binding site
multiple dependent binding site
Types of ligand
cofactor
Metal
Substrat
Inhibitor
Metods for detection of ligand binding
x-ray crystallography
NMR
SPR biacore
Radioactivity
ITC
Fluorescence
Common experimental setup for ligand binding
Equilibrium dialysis
Competitive labeling (Fluorescence)
Single site binding
P + L ↔ PL
Ka = ⟦PL⟧ / ⟦P⟧⟦L⟧ Kd = ⟦P⟧⟦L⟧ / ⟦PL⟧
Fraction of saturation
Y = ⟦PL⟧ / ⟦PL⟧ + ⟦P⟧ = ⟦L⟧ / Kd + ⟦L⟧
Multiple independent binding sites
Scatchard Plot
Scatchard Plot
R/⟦A⟧ = nKa - KaR
R = Ka⟦A⟧ / 1 + Ka⟦A⟧
n = number of binding site Ka = 1 / Kd
R / ⟦A⟧ vs R
Cooperativity
Hill plot
Hill plot
log(R / 1-R) = log Ka + n log⟦A⟧
log R / (1-R) vs log⟦A⟧
Direct plot
R vs ⟦A⟧
Reciprocal plot
1 / R vs 1 / ⟦A⟧
logarithmic plot
R vs log ⟦A⟧
Strat of direct plot
Sigmoidal → cooperative, use hill plot
Hyperbolic → Noncooperative
