Choline oxidation by intact chloroplasts isolated directly from spinach leaves
Illuminated chloroplasts derived from spinach leaf protoplasts synthesize betaine from choline via the intermediate betaine aldehyde (BAL) (PNAS 82:3678). Photosynthetically active chloroplasts isolated directly from spinach leaves oxidized (/sup 14/C)choline in the light at rates 10 times higher (25-80 nmol/mg chl b) than protoplast-derived chloroplasts. Up to 20% of the (/sup 14/C)choline supplied during a 30 min incubation was oxidized in the light; the main product was (/sup 14/C)BAL. Rates of (/sup 14/C)choline oxidation in darkness were only 5-30% of rates in light. Light-dependent (/sup 14/C)choline oxidation was abolished by DCMU and 5 mM DTT. Pre-illumination of the chloroplasts did not promote (/sup 14/C)choline oxidation in darkness. The uncouplers nigericin and CCCP at concentrations which eliminated CO/sub 2/-dependent O/sub 2/ evolution did not affect (/sup 14/C)choline oxidation in the light. They hypothesize that (/sup 14/C)choline oxidation is not dependent upon light activation of an enzymatic system or upon the electrochemical proton gradient but requires an oxidant generated in the light.
- Research Organization:
- Michigan State Univ., East Lansing
- DOE Contract Number:
- AC02-76ER01338
- OSTI ID:
- 5126226
- Journal Information:
- Plant Physiol., Suppl.; (United States), Vol. 80:4; Conference: Annual meeting of the American Society of Plant Physiologists, Baton Rouge, LA, USA, 8-12 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHOLINE
OXIDATION
LEAVES
CHLOROPLASTS
CARBON 14 COMPOUNDS
LABELLING
SPINACH
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
DRUGS
FOOD
HYDROXY COMPOUNDS
LABELLED COMPOUNDS
LIPOTROPIC FACTORS
ORGANIC COMPOUNDS
PLANTS
QUATERNARY COMPOUNDS
VEGETABLES
550201* - Biochemistry- Tracer Techniques