4-Aminobutyraldehyde Dehydrogenase Activity in Rat Brain

Abstract: An enzyme with NAD⁺-dependent 4-aminobutyraldehyde dehydrogenase activity was purified about 360-fold from rat brain extract. AMP-Sepharose chromatography was effective in separating the enzyme from other NAD⁺-dependent aldehyde dehydrogenases included in the extract. The K _ms for the substrates NAD⁺ and 4-aminobutyraldehyde were 4.8 × 10⁻⁴ and 8.3 × 10⁻⁵ M , respectively. The pH optimum for the enzyme was about 8.0. The ratio of activities toward 4-aminobutyraldehyde, propionaldehyde, succinate semialdehyde, and benzaldehyde was 1.00:0.17:0.24:0.09:0.03 when the activity toward 4-aminobutyraldehyde was set equal to 1.00. The enzyme activity in subcellular fractions of rat brain was localized in cytosol.