In vitro inhibition of the paraoxonase from human serum with sulfonamide

Abstract

This study was conducted to determine the in vitro effects of sulfonamide on human serum paraoxonase (PON1) activity. The enzyme was purified by two-step using ammonium sulfate precipitation and sepharose-4B-L-tyrosine-1-napthylamine hydrophobic interaction chromatography.
Sulfonamide was an effective inhibitor on purified human serum PON1 activity for phenylacetate and paraoxon as substrates with IC50 values of 0.22 and 0.81 mM, respectively. The kinetics of interaction of
sulfonamide with the purified enzyme indicated a different inhibition pattern for two substrates. Sulfonamide showed a non-competitive inhibition with Ki  of 0.0037 ± 0.0009 mM for phenylacetate and competitive inhibition with Ki of 0.0057 ± 0.0002 mM for paraoxon.