An improved choline monooxygenase assay
- Michigan State Univ. Plant Research Lab., East Lansing (United States)
Glycine betaine accumulates in leaves of plants from several angiosperm families in response to drought or salinization. Its synthesis, from the oxidation of choline, is mediated by a two step pathway. In spinach the first enzyme of this pathway is a ferredoxin-dependent choline monooxygenase (CMO). In order to purify this enzyme a sensitive and reliable assay is necessary. Two types of modifications were explored to improve the existing assay. (1) Ferredoxin reduction - one way of providing reduced Fd to CMO is by the addition of isolated spinach thylakoids in the assay mixture. In order to optimize the reduction of Fd two different systems were compared: (a) where only PS is active, by adding DCMU to inhibit electron transport from PS II and DAD as electron donor for PS I; (b) where both PS II and PS I are active. (2) Betaine aldehyde estimation - to simplify this, it is possible to couple the CMO reaction with betaine aldehyde dehydrogenase (BADH) from E. coli. BADH converts betaine aldehyde to betaine as it is formed in the assay, eliminating the need for a chemical oxidation step.
- OSTI ID:
- 5403575
- Report Number(s):
- CONF-9107184-; CODEN: PPYSA
- Journal Information:
- Plant Physiology, Supplement; (United States), Vol. 96:1; Conference: Annual meeting of the American Society of Plant Physiology, Albuquerque, NM (United States), 28 Jul - 1 Aug 1991; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
OXIDOREDUCTASES
BIOCHEMICAL REACTION KINETICS
ALDEHYDES
BETAINE
BIOLOGICAL PATHWAYS
BIOLOGICAL STRESS
BIOSYNTHESIS
CHOLINE
DROUGHTS
GLYCINE
LEAVES
PHOTOSYNTHETIC REACTION CENTERS
SALINITY
SPINACH
ALCOHOLS
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
CARBOXYLIC ACIDS
DRUGS
ENZYMES
FOOD
HYDROXY COMPOUNDS
KINETICS
LIPOTROPIC FACTORS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PLANTS
PROTEINS
QUATERNARY COMPOUNDS
REACTION KINETICS
SYNTHESIS
VEGETABLES
550200* - Biochemistry