Betaine aldehyde dehydrogenase from spinach leaves: purification, in vitro translation of the mRNA, and regulation by salinity.
Spinach (Spinacia oleracea L.) leaves contain a nuclear-encoded chloroplastic betaine aldehyde dehydrogenase (EC 1.2.1.8) which is induced several-fold by salinization. Betaine aldehyde dehydrogenase was purified 2400-fold to homogeneity with an overall yield of 14%. The procedure included fractional precipitation with ammonium sulfate, followed by ion-exchange, hydrophobic interaction, and hydroxyapatite chromatography in open columns, and ion-exchange and hydrophobic interaction chromatography in a fast-protein liquid chromatography system. The betaine aldehyde dehydrogenase had a pI of 5.65, and a broad pH optimum between 7.5 and 9.5. The Km values for NAD+ and NADP+ were 20 and 320 microM, respectively; the Vmax of the reaction with NADP+ was 75% of that with NAD+. The native enzyme is a dimer with subunits of Mr 63,000. Highly specific antiserum was raised against the native enzyme, and was used in conjunction with cell-free translation of leaf poly(A)+ RNA to show (a) that betaine aldehyde dehydrogenase is synthesized as a precursor of Mr 1200 higher than the mature polypeptide, and (b) that both chronic salt stress and salt shock provoke a several-fold increase in the level of translatable message for the enzyme.
Weretilnyk
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EA
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing 48824.
Hanson
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AD
D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000302:isolation & purification*; D050728:Betaine-Aldehyde Dehydrogenase; D015153:Blotting, Western; D002736:Chloroplasts / Q000201:enzymology*; D002845:Chromatography / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction / Q000187:drug effects; D004792:Enzyme Precursors / Q000378:metabolism; D007526:Isoelectric Point; D008970:Molecular Weight; D010945:Plants, Edible / Q000201:enzymology*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000302:isolation & purification*; D012965:Sodium Chloride / Q000494:pharmacology*
D004792:Enzyme Precursors; D012333:RNA, Messenger; D012965:Sodium Chloride; D000445:Aldehyde Oxidoreductases; D050728:Betaine-Aldehyde Dehydrogenase