ИСТИНА

In the current study we analyzed integral kinetics of cyclooxygenase reaction at different AA and Tween-20 contents in the reaction medium. The initial reaction rate grows as AA content increases, but the final yield of reaction product declines. The data obtained can be described by theoretical model that takes into account cooperative interactions between PGHS subunits. In these interactions, constants of interactions between enzyme and substrate and rate constants of inactivation in the course of reaction depend of the condition of the neighbor monomer (it is not bound by AA, it is bound by AA or inactivated in the course of reaction). Increasing of Tween-20 content leads to decline of initial reaction rate and to growth of final yield of the reaction product. These observations agree with previously obtained results showing that increasing of Tween-20 content leads to AA redistribution between water and hydrophobic phases and decreasing of real AA concentrations inside these phases.The results obtained in this study confirm that changes in AA contents lead to manifestation of cooperative interactions between PGHS subunits. It should be taken into account during the investigation of prostaglandin synthesis and pharmacological effects of NSAIDs in vivo.