B. Samori et al., CHEMICAL-REACTIVITY WITHIN A SMECTIC-B LIQUID-CRYSTALLINE PHASE - A MODEL OF ENZYME CATALYSIS, Liquid crystals, 15(2), 1993, pp. 217-231
The rearrangement of allyl p-dimethylaminobenzenesulphonate (ASE) to f
orm a zwitterionic product has already been recognized as an effective
probe for the study of reactivity within the smectic B phase [4,5,19]
. We have used deuterium NMR, linear dichroism and X-ray diffraction t
echniques to investigate the phase diagram of the ASE-OS35 reaction sy
stem. The partitioning of the reactant molecules between coexisting sm
ectic, nematic and/or isotropic phases and the structural organization
of the smectic catalytic host at different temperatures and reactant
guest concentrations have been characterized. On the basis of these me
asurements, a model of ASE reactivity in smectic solvents has been dev
eloped. The reaction takes place provided that coexisting isotropic or
nematic phases are present to act as a reservoir for the ASE reactant
molecules prior to their entering the smectic phase; they then react
and leave the smectic phase as a zwitterionic product. The analogy bet
ween this model of reactivity within smectic phases and the Michaelis-
Menten enzyme processes is discussed. This relationship opens up the i
ntriguing possibility of designing new experiments with which to inves
tigate further liquid crystalline models of enzyme catalysis.