Table I.

Biophysical Methods to characterize macromolecular interactions

	Sedimentation Equilibriuma	Sedimentation Velocityb	Isothermal Titration Calorimetryc	Surface Plasmon Resonanced	Light Scatteringe	Fluorescencef
Component Properties	Mass	Mass and Hydrodynamics	-	-	Mass and Shape	Hydrodynamics
Complex Properties	Stoichiometry	Stoichiometry	Molar Ratio	Molar Ratio	Stoichiometry	Molar Ratio
Species Resolution	Resolved Complexes	Resolved Complexes	Fractional Saturation	Fractional Saturation	Resolved Complexesg	Fractional Saturation
Kd Range (M)	10−3 – 10−9	10−4 – 10−8	10−3 – 10−8 (10−2 – 10−12)h	10−3 – 10−12	-	10−3 – 10−12
Additional Information	-	Kinetics and Hydrodynamics	Thermodynamics	Kinetics	-	-
Material Requirements	20–120µL	400 µL	1.5 mL	µL	-	µL- nL

^aReferences: 4, 21, 28–32, 48

^bReferences: 2, 3, 22, 23, 30, 48

^cReferences: 49, 50

^dReferences: 51, 52

^eReferences: 53–55

^fReferences: 56–58

h In dynamic light scattering resolution is achieved by analysis of the autocorrelation function as a continuous distribution of diffusing species (59).

^gLigand displacement and proton linkage techniques greatly extend the accessible K_d range for low affinity (60) and high affinity (61, 62) interactions measured by isothermal titration calorimetry.