Reagent	Amount	Final concentration
1 M Tris-HCl, pH 7.4	20 mL	20 mM
NaCl	17.5 g	300 mM
Imidazole	34 g	500 mM

Adjust pH to 7.4 at 25°C, add DI water up to 1 L and filter the buffer using a 0.22 μm filter unit. The buffer can be stored at 4°C for one month.