Metabolic relationships between monogalactosyldiacylglycerol and digalactosyldiacylglycerol molecular species in Dunaliella salina
Dunaliella salina cells were pulse-labeled for 2 min with (/sup 14/C)palmitic acid, (/sup 14/C)oleic acid, or (/sup 14/C)lauric acid in order to trace the pathway of galactolipid biosynthesis and desaturation. Through the use of high performance liquid chromatography it was possible to follow the movement of radioactivity through many individual molecular species of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) for periods of 24 h and, in some cases, as much as 120 h. Analysis of the fatty acid fluxes permitted us to refine current views regarding biosynthesis of the predominantly prokaryotic galactolipids. The initial D. salina MGDG molecular species, containing paired oleate and palmitate (18:1/16:0), can follow two metabolic routes. If the palmitoyl chain is desaturated to 16:1, the resulting 18:1/16:1 MGDG is subject to rapid further desaturation to varying degrees, and a part of these products is subsequently galactosylated to DGDG. Contrary to widely held opinions, these DGDG molecular species can themselves be further desaturated toward a 18:3/16:4 final product. In a separate series of reactions, a smaller portion of the nascent 18:1/16:0 MGDG is directly galactosylated to 18:1/16:0 DGDG. This molecular species can then be sequentially desaturated to 18:2/16:0 DGDG and 18:3/16:0 DGDG. However, there is only very limited desaturation of the palmitoyl group attached to these molecular species.
- Research Organization:
- Univ. of Texas, Austin
- OSTI ID:
- 6332834
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 16
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLYCOLIPIDS
BIOSYNTHESIS
ALGAE
CARBON 14 COMPOUNDS
HEXADECANOIC ACID
LIQUID COLUMN CHROMATOGRAPHY
OLEIC ACID
STRUCTURE-ACTIVITY RELATIONSHIPS
TRACER TECHNIQUES
CARBOHYDRATES
CARBOXYLIC ACIDS
CHROMATOGRAPHY
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPIDS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PLANTS
SACCHARIDES
SEPARATION PROCESSES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques