Reaction Mechanisms in Confined Media

Nucleophillic attack of a hydroxide ion on substrates is a common part of reaction mechanisms in hydrolytic enzymes, for example, carbonic anhydrase or carboxypeptidase.  These reactions take place in the enzyme interior where there is a deficiency of water.  While many studies of the nucleophilicity of hydroxide have been carried out in bulk water, little is known about its reactivity when only a few water molecules are present.  Measuring hydroxide's abiloity to act as a nucleophile in a water deficient environment is therefore important for a complete understanding of these enzymatic processes.  We have chosen to study the hydrolysis of a water soluble dye by hydroxide ion confined within reverse micelles (RMs).  These RMs are spherical assemblies of surfactants, water and oil.  The numbers of waters present in RMs can be easily controlled and thus provide information regarding the nucleophilicity of hydroxide ions in water deficient environments.  In this work we have studied the reaction of hydroxide with crystal violet in bulk water and reverse micelles.  We have demonstrated that hdroxide ion's nucleophilicity is enhanced upon confinement within an RM.  The poster presents the results of our studies and the function of nucleophilicity on the concentration of water.