Involvement of ferredoxin in desaturation of lipid-bound oleate in chloroplasts

Journal Article · Sat Sep 01 04:00:00 EDT 1990 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.94.1.214· OSTI ID:5962121

Schmidt, H; Heinz, E ^[1]

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1. Institut fuer Allgemeine Botanik der Universitaet Hamburg (West Germany)

Intact spinach (Spinacia oleracea) chloroplasts, pulse-labeled with ({sup 14}C)acetate, desaturate newly formed fatty acids as ester groups of monogalactosyl diacylglycerol in a subsequent chase in the dark. Rupture of pulse-labeled chloroplasts by addition of a detergent solution 3-((3-cholamidopropyl)dimethylammonio)-1-propane sulfonate preserves part of this desaturation activity. Direct addition of different free fatty acids together with appropriate cofactors to detergent-ruptured chloroplasts results in fatty acid labeling of monogalactosyl diacylglycerol. During subsequent incubation these lipid-linked fatty acids are desaturated, i.e. 18:1 to 18:2 and 18:3 and to a small extent also 16:0 to 16:3. The formation of 18:2 was also observed after incorporation of 18:1 into sulfolipid and phosphatidyl choline. Density gradient centrifugation separated a membrane fraction from detergent-ruptured chloroplasts which in the presence of appropriate cofactors incorporated 18:1 and 18:2 into the above-mentioned lipids. In the light, desaturation was dependent on added ferredoxin, whereas in the dark, in addition to ferredoxin NAD(P)H was also required. Preliminary evidence for the involvement of membrane-bound ferredoxin:NADP oxidoreductase (FNR) as a third component of desaturation in the dark was obtained by inhibitor studies including antibodies against FNR. Desaturation of lipid-bound 18:1 and 18:2 resembles stearoyl-ACP desaturation with respect to its requirement of reduced ferredoxin and oxygen.

• OSTI ID: 5962121
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 94:1; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
CARBON 14 COMPOUNDS
CELL CONSTITUENTS
CHLOROPLASTS
ESTERS
FERREDOXIN
FOOD
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPIDS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
METABOLISM
METALLOPROTEINS
OILS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PLANTS
PROTEINS
SPINACH
TRACER TECHNIQUES
TRIGLYCERIDES
TRIOLEIN
VEGETABLES