Esterase-like activity of human serum albumin: enantioselectivity in the burst phase of reaction with p-nitrophenyl alpha-methoxyphenyl acetate.

Enantioselectivity in the burst phase of the reactions of D- and L-p-nitrophenyl alpha-methoxyphenyl acetates with human and bovine serum albumin was investigated kinetically in pH 7.4 phosphate buffer and at 25 degrees C. The burst phase was measured under the conditions of excess albumin over the enantiomer. Both albumins reacted with D enantiomer about threefold faster than L enantiomer, mainly due to the catalytic step and not due to the binding step. The reactivity of human serum albumin toward the enantiomers was four- to fivefold higher than that of bovine serum albumin.