NAD-dependent aminoaldehyde dehydrogenase (AMADH, EC 1.2.1.-) from Avena shoots was purified by DEAE Sephacel, hydroxyapatite, 5'-AMP Sepharose 4B, Mono Q, and TSK-GEL column chromatographies to homogeneity by the criterion of native PAGE. SDS-PAGE yielded a single band at a molecular mass of 55 kDa. IEF studies showed a band with a p I value of 5.3. In contrast to AMADHs from other species, the TSK-GEL chromatography showed that AvenaAMADH exists as a monomer in the native state. The purified enzyme catalyzed the oxidations of 3-aminopropionaldehyde (APAL), 4-aminobutyraldehyde (ABAL) N-(3-aminopropyl)-4-aminobutyraldehyde (APBAL), and 4-guanidinobutyraldehyde (GBAL), but not of betaine aldehyde or indoleacetaldehyde. The K(m) values for APAL, ABAL, and GBAL were 1.5x10(-6), 2.2x10(-6), and 1.3x10(-5) M, respectively. Although N-terminal amino acid sequence of Avena AMADH could not be determined due to a modification of the amino residue, the sequence of the fragment of AMADH cleaved by V8 protease showed greater similarity to the barley BADH than to the pea AMADH.