Patent ID: 6849458

Claim:
A method for identifying a ligand that binds to a protein, comprising the steps of: (1) receiving unfolding data that indicates thermal unfolding as a function of temperature for a protein incubated with a molecule tested for binding; (2) determining an unfolding temperature midpoint for the protein in the presence of the molecule from the unfolding data; (3) comparing the unfolding temperature midpoint for the protein incubated with the ligand with the unfolding temperature midpoint for the protein in the absence of any molecules tested for binding; and (4) determining that the molecule tested for binding binds to the protein when a difference between the unfolding temperature midpoint for the protein in the presence of the molecule and unfolding temperature midpoint for the protein in the absence of any molecules tested for binding exceeds a threshold; and (5) estimating the ligand binding affinity at the unfolding temperature midpoint according to: K L T m = exp ⁢ { - Δ ⁢ ⁢ H u T 0 R ⁡ [ 1 T m - 1 T 0 ] + Δ ⁢ ⁢ C pu R ⁡ [ ln ⁡ ( T m T 0 ) + T 0 T m - 1 ] } [ L T m ] where, Kf L T m is a ligand association constant at T m T m is a midpoint temperature for the protein unfolding transition in the presence of the ligand; T 0 is a midpoint temperature for the protein unfolding transition in the presence of the ligand; ΔH u T 0 is an enthalpy of protein unfolding in the absence of ligand at T 0 ; ΔC pu is a change in heat capacity upon protein unfolding in the absence of ligand; [L T m ] is a free ligand concentration at T m ;and R is the gas constant.