KINETICS OF BUTYRYLCHOLINESTERASE IN REVERSED MICELLES UNDER HIGH-PRESSURE

The combined effects of high pressure and reversed micelles have been studied to modulate the catalytic behaviour of butyrylcholinesterase. The purpose of this study was to determine whether the conformational plasticity of the enzyme is altered by entrapment in reversed micelles . The presence of soman, an irreversible inhibitor of cholinesterase w as used to bring to the fore a possible modification of the enzyme beh aviour in this system under pressure. Results show differences between enzyme in conventional medium and in reversed micelles regarding the mechanism of BuChE catalyzed hydrolysis of acetylthiocholine. In both systems, the enzyme displays a non-Michaelian behaviour with this subs trate. In conventional medium the kinetics is multiphasic with an acti vation phase followed by an inhibition phase at high concentration. In reversed micelles there is inhibition by excess substrate but the act ivation phase is missing. This behaviour may be the result of a change of the enzyme conformational plasticity when is entrapped in reversed micelles.