Structure and reactivity of aerosol-OT reversed micelles containing α-chymotrypsin

Abstract

The structure and reactivity of a-chymotrypsin solubilized in biological buffer-sodium bis(2-ethylhexyl)sulfosuccinate (AOT)-2,2,4-trimethylpentane (isooctane) reversed micelles, have been studied at various water/ surfactant molar ratios (coo) and protein concentrations using synchrotron radiation X-ray small-angle scattering and enzymatic activity measurements. Two types of a-chymotrypsins and two different substrates @-nitrophenyl acetate and p-nitrophenyl caprylate) were used. The scattering experiments show that a-chymotrypsins are entrapped in t h e water pools. In t h e low coo range (0 < coo < 12) oligomeric AOT reversed micellar formation occurs as a metastable state and simultaneously t h e enzymatic activity is enhanced significantly for both types of a-chymotrypsins, showing a maximum activity at coo = 12 for both substrates. The results from the scattering

Mechanism of protein extraction from the solid state by water-in-oil microemulsions

“…Moreover, values of the AOT aggregation number, N AOT , employed in the calculation of f values are based on non-protein-containing, or ''empty,'' w/o-MEs. The difference in size between empty and CHY-containing w/o-MEs is insignificant (Christ and Schurtenberger, 1994;Hirai et al, 1995). Of interest, a recent report suggests that in the w o range 15-30 CHY solubilizes into w/o-MEs as dimers (Oldfield et al, 1996).…”

“…Solubilization at large w o values (e.g., CHY) was primarily driven by the affinity of proteins for w/o-ME-encapsulated water (Leser and Luisi, 1990). For example, proteins such as LYS and cytochrome c, which strongly interact with the AOT w/o-ME interface, have a SPE solubilization maximum at low w o values, but proteins which solubilize in the aqueous nanophase and have little interaction with the interface, such as CHY, have solubilization maxima at high w o values (Adachi and Harada, 1993;Christ and Schurtenberger, 1994;Hirai et al, 1995;Leser and Luisi, 1990;Lye et al, 1995).…”

Surfactant tail length-dependent lipase activity profile in cationic water-in-oil microemulsions

“…The space/area at the solubilization site of enzymes also expectedly have a crucial role in its efficiency by rendering flexible conformation to the protein [43][44][45][46]. So, the higher surface area occupied by the AOT head group as well as the absence of alcohol may have provided flexibility to the secondary structure of lipase [47][48][49], leading to its superior activity.…”

Solubilization of enzymes in water-in-oil microemulsions and their rapid and efficient release through use of a pH-degradable surfactant

“…Lysozyme strongly interacts with ionic surfactants (Hayes 1997;Lye et al 1995) while chymotrypsin resides in the interior of microemulsion droplets and to interact much more weakly with surfactants (Hirai et al 1995). The solubility of lysozyme and chymotrypsin were 1.5 and 2 g l -1 , respectively, in 0.15 M surfactant w/omicroemulsion solution that possesses a watersurfactant mole ratio, or w o value, of 11.2, and at 10 g protein l -1 for each in 1.2 M surfactant of w/o-microemulsion solution, w o = 11.2.…”