Horse Liver Alcohol Dehydrogenase as a Probe for Nanostructuring Effects of Alcohols in Water/Nonionic Surfactant Systems

The kinetics of alcohol oxidation catalyzed by the enzyme horse liver alcohol dehydrogenase (HLADH) is studied in water/alcohol/C 12 E 23 systems with a series of n -alcohols ranging from ethanol to 1-decanol or with α,ω-alkandiols, namely, 1,5-pentanediol and 1,7-heptanediol. Essentially, the water-rich part of the ternary systems is examined, either without C 12 E 23 or at several constant C 12 E 23 concentrations above the cmc (1, 8, and 22 mass %). The substrate inhibition of the enzyme allows one to infer alcohol partition coefficients between the outer aqueous pseudophase and the surfactant aggregation pseudophase. In the case of short-chain n -alcohol (ethanol, 1-propanol) and alkandiol (1,5-pentanediol) systems, the alcohol seems to remain in the aqueous pseudophase, whereas in the case of middle- and long-chain n -alcohol (1-butanol to 1-decanol) and alkandiol (1,7-heptandiol) systems, the alcohol participates in the structuration of the micelle.