Ss. Lee et al., ENZYME SOLUBILIZATION IN A REVERSED MICELLAR MICROREACTOR WITH A BILE-SALT COSURFACTANT, Journal of colloid and interface science, 193(1), 1997, pp. 32-40
Spectroscopic techniques (UV absorbance, circular dichroism, fluoresce
nce emission and anisotropy, and light scattering) were used to invest
igate enzyme solubilization in Aerosol-OT (AOT) reversed micelles in w
hich a bile salt, sodium taurocholate (NaTC), is used as a novel cosur
factant. NaTC significantly increases the water capacity and size of t
he reversed micelles through surfactant reorganization. The solubiliza
tion of several enzymes, including lysozyme, chymotrypsin, lipase, lip
oxidase, carbonic anhydrase, and ribonuclease A, was demonstrated. The
se enzymes, ranging in mass from 10(4) to 10(5) Da, are incorporated i
n the micelles in stable, optically transparent solutions. Several oth
er proteins were not successfully solubilized. The presence of NaTC in
the reversed micelles significantly altered the conformations of the
solubilized enzymes, apparently by promoting unfolding of the enzyme t
hrough interactions with the interior micellar interface. Lysozyme and
lipase respond to solubilization in the AOT/NaTC micelles by altering
their conformations to accommodate the micellar structure. The effect
of NaTC is greatest far lysozyme, inducing a higher degree of order a
nd helicity in the enzyme structure. Chymotrypsin, on the other hand,
disrupts the micellar structure and reorganizes the surfactants to acc
ommodate its own preferred conformation, Addition of NaTC to the rever
sed micelles causes a 3-fold increase in the enzymatic activity of sol
ubilized chymotrypsin. (C) 1997 Academic Press.