ADH activity in gels was detected according to Seymour
and Lazarus [15] with minor modifications. Instead of native
gels, we used isoelectric focusing gels and a PhastSystem
for separation (Pharmacia Biotech, Uppsala, Sweden).
Gels were soaked in 20 mM BisTris, pH 7.0, containing 2
mM NADH or NADPH for 15 min on ice. Excess of buffer
was drained and the gel was covered with filter paper strips
soaked in substrate solution, i.e. 10 mM hexanal or 10 mM
3-methylbutanal in 20 mM BisTris, pH 7.0. After approx. 5
min, filter paper was removed and gels were exposed to
ultraviolet light and analyzed for disappearance of fluorescence
indicating reductase activity.