Ligand binding properties and esterase-like activity of recombinant human serum albumin

The ligand binding properties and esterase-like activity of recombinant human serum albumin (rHSA) expressed by Pichia pastoris were compared with those of plasma derived human albumin (pHSA). The binding of long fatty acid ions was determined by the equilibrium partition method using radiolabeled palmitate. The association constants and the number of binding sites of diazepam, salicylate and warfarin were determined by specific and nonspecific binding models. The high affinity binding of bilirubin was kinetically determined from the oxidation rate of free bililubin in the binding mixture. The binding parameters of these five ligands obtained with rHSA were within the same range observed with pHSA preparations. The kinetic parameters for hydrolytic activity of rHSA toward p-nitrophenyl acetate was also similar to pHSA. These results indicate that rHSA and pHSA have the same functional property.