Lipid composition of organelles from germinating castor bean endosperm
Glyoxysome, endoplasmic reticulum, mitochondria, and proplastid fractions were isolated from endosperm of castor beans (Ricinus communis) germinated for 5 days at 30 C. Samples from sucrose density gradients were diluted with 0.15 M KCl and the membranes pelleted. Lipid extracts of these membranes were analyzed for phosphoglyceride, acyl lipid, and sterol content. The endoplasmic reticulum contains 1.24 ..mu..mol of phosphoglyceride per mg of protein; the mitochondria, 0.65 ..mu..mol/mg; and the glyoxysome membranes, 0.55 ..mu..mol/mg. Phosphatidyl choline and phosphatidyl ethanolamine are the most abundant lipids in all membranes studied, accounting for 70% or more of the lipid phosphorus and 50% or more of the fatty acid. Glyoxysome membranes and endoplasmic reticulum also contain phosphatidyl inositol (respectively, 9 and 17% of the lipid phosphorus) and free fatty acids (13% of the total fatty acid in each). Compared with other organelles, mitochondrial membranes have more phosphatidyl ethanolamine relative to phosphatidyl choline and are characterized by the presence of cardiolipin, in which 80% of the fatty acid is linoleate. The relative amounts of linoleate, palmitate, oleate, stearate, and linolenate in each of the phosphotoglycerides are constant regardless of the membrane source. Stimasgasterol and ..beta..-sitosterol are present in the membranes (1 to 9 nmol each/mg protein). The data provide further evidence that glyoxysome membranes are derived from the endoplasmic reticulum but at the same time indicate some differentiation.
- Research Organization:
- Univ. of California, Santa Cruz, CA (United States)
- OSTI ID:
- 5238022
- Journal Information:
- Plant Physiol.; (United States), Vol. 59:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANOIDS
LIPIDS
AMINES
BIOCHEMISTRY
CARBOXYLIC ACIDS
CASTOR
CHEMICAL COMPOSITION
CHOLINE
ENDOPLASMIC RETICULUM
ENDOSPERM
ESTERS
ETHANOL
GERMINATION
HEXADECANOIC ACID
LINOLENIC ACID
MEMBRANES
MITOCHONDRIA
OLEIC ACID
PHOSPHOLIPIDS
PHOSPHORUS
PLANTS
SACCHAROSE
STEARATES
ALCOHOLS
AMMONIUM COMPOUNDS
BIOMASS
CARBOHYDRATES
CARBOXYLIC ACID SALTS
CELL CONSTITUENTS
CHEMISTRY
DISACCHARIDES
ELEMENTS
ENERGY SOURCES
HYDROXY COMPOUNDS
LIPOTROPIC FACTORS
MEDICINAL PLANTS
MONOCARBOXYLIC ACIDS
NONMETALS
OLIGOSACCHARIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PLANT TISSUES
QUATERNARY COMPOUNDS
RENEWABLE ENERGY SOURCES
SACCHARIDES
550200* - Biochemistry