Is acetylcarnitine a substrate for fatty acid synthesis in plants

Journal Article · Wed Mar 31 23:00:00 EST 1993 · Plant Physiology; (United States)

OSTI ID:6389334

Roughan, G ^[1]; Post-Beittenmiller, D; Ohlrogge, J ^[2]; Browse, J ^[3]

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1. Horticulture Research Inst., Auckland (New Zealand)
2. Michigan State Univ., East Lansing (United States)
3. Washington State Univ., Pullman (United States)

Long-chain fatty acid synthesis from [1-[sup 14]C]acetylcarnitine by chloroplasts isolated from spinach (Spinacia oleracea), pea (Pisum sativum), amaranthus (Amaranthus lividus), or maize (Zea mays) occurred at less than 2% of the rate of fatty acid synthesis from [1-[sup 14]C]acetate irrespective of the maturity of the leaves or whether the plastids were purified using sucrose or Percoll medium. [1-[sup 14]C]Acetylcarnitine was not significantly utilized by highly active chloroplasts rapidly prepared from pea and spinach using methods not involving density gradient centrifugation. [1-[sup 14]C]Acetylcarnitine was recovered quantitatively from chloroplast incubations following 10 min in the light. Unlabeled acetyl-L-carnitine (0.4 mM) did not compete with [1-[sup 14]C]acetate (0.2 mM) as a substrate for fatty acid synthesis by any of the more than 70 chloroplast preparations tested in this study. Carnitine acetyltransferase activity was not detected in any chloroplast preparation and was present in whole leaf homogenates at about 0.1% of the level of acetyl-coenzyme A synthetase activity. When supplied to detached pea shoots and detached spinach, amaranthus, and maize leaves via the transpiration stream, 1 to 4% of the [1-[sup 14]C]acetylcarnitine and 47 to 57% of the [1-[sup 14]C]acetate taken up was incorporated into lipids. Most (78--82%) of the [1-[sup 14]C]acetylcarnitine taken up was recovered intact. It is concluded that acetylcarnitine is not a major precursor for fatty acid synthesis in plants. 29 refs., 5 tabs.

• OSTI ID: 6389334
• Journal Information: Plant Physiology; (United States), Journal Name: Plant Physiology; (United States) Vol. 101:4; ISSN PLPHAY; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CARBOXYLIC ACIDS
CARNITINE
CELL CONSTITUENTS
CEREALS
CHLOROPLASTS
FOOD
GRAMINEAE
HOMOGENATES
HYDROXY ACIDS
LEAVES
LEGUMINOSAE
LILIOPSIDA
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MAIZE
ORGANIC ACIDS
ORGANIC COMPOUNDS
PISUM
PLANTS
PRECURSOR
SPINACH
SUBSTRATES
SYNTHESIS
TRANSPIRATION
VEGETABLES
VITAMIN B GROUP
VITAMINS