Mechanistic studies of the hydrolysis of p-nitrophenyl sulfate catalyzed by arylsulfatase from Helix pomatia

The kinetics of the hydrolysis of small aryl substrate p- nitrophenyl sulfate (p- NPS) catalyzed by arylsulfatase from Helix pomatia was studied at a wide range of temperatures as well as at ambient and elevated pressures. The employed kinetic assay techniques allow for the determination of activation entropy (Delta S-not equal), activation enthalpy (Delta H-not equal), as well as activation volume (Delta V-not equal) which suggested associative interchange character of the sulfate ester hydrolysis. The pH dependence obtained for catalytic parameters suggests that two protonation/deprotonation reactions can occur and the optimum pH for the catalytic activity was also detected.