Enzyme and organic solvents: horse liver alcohol dehydrogenase in non-ionic microemulsion: stability and activity.

In a microemulsion made with Triton X-100, the stability of the enzymatic activity was higher than in ionic microemulsions. The stability increased with water content. The kinetic constants (Michaelis constant of NAD+ and maximum velocity) were close to those found in the previously studied microemulsions. The Michaelis constant of NAD+ expressed with respect to the buffer volume was higher than in water. The pH dependence of the kinetic constants in this microemulsion was determined. The activity determined by NAD+ reduction decreased with water content, whereas the redox activity determined via butanol oxidation coupled to retinal reduction was only slightly reduced.