title: Enzymatic characterization of peroxisomal and cytosolic betaine aldehyde dehydrogenases in barley.
abstract: Betaine aldehyde dehydrogenase (BADH; EC 1.2.1.8) is an important enzyme that catalyzes the last step in the synthesis of glycine betaine, a compatible solute accumulated by many plants under various abiotic stresses. In barley (Hordeum vulgare L.), we reported previously the existence of two BADH genes (BBD1 and BBD2) and their corresponding proteins, peroxisomal BADH (BBD1) and cytosolic BADH (BBD2). To investigate their enzymatic properties, we expressed them in Escherichia coli and purified both proteins. Enzymatic analysis indicated that the affinity of BBD2 for betaine aldehyde was reasonable as other plant BADHs, but BBD1 showed extremely low affinity for betaine aldehyde with apparent K(m) of 18.9 microM and 19.9 mM, respectively. In addition, V(max)/K(m) with betaine aldehyde of BBD2 was about 2000-fold higher than that of BBD1, suggesting that BBD2 plays a main role in glycine betaine synthesis in barley plants. However, BBD1 catalyzed the oxidation of omega-aminoaldehydes such as 4-aminobutyraldehyde and 3-aminopropionaldehyde as efficiently as BBD2. We also found that both BBDs oxidized 4-N-trimethylaminobutyraldehyde and 3-N-trimethylaminopropionaldehyde.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Kazuya
authors.initials: K
authors.lastname: Hori
authors.forename: Keiko
authors.initials: K
authors.lastname: Ozaki
authors.forename: Yuka
authors.initials: Y
authors.lastname: Yokota
authors.forename: Shiro
authors.initials: S
authors.lastname: Mitsuya
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ichiyanagi
authors.forename: Tasuku
authors.initials: T
authors.lastname: Hattori
authors.forename: Tetsuko
authors.initials: T
authors.lastname: Takabe
mesh_terms: D050728:Betaine-Aldehyde Dehydrogenase / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D001467:Hordeum / Q000201:enzymology*; D020675:Peroxisomes / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D010940:Plant Proteins; D050728:Betaine-Aldehyde Dehydrogenase