Docosahexaenoate-containing molecular species of glycerophospholipids from frog retinal rod outer segments show different rates of biosynthesis and turnover
The authors have studied the de novo synthesis and subsequent turnover of major docosahexaenoate-containing molecular species in frog rod outer segment (ROS) phospholipids following intravitreal injection of (2-/sup 3/H)glycerol. On selected days after injection, ROS were prepared and phospholipids extracted. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS) were isolated and converted to diradylglycerols with phospholipase C. Diradylglycerols were derivatized with benzoic anhydride and resolve into diacylglycerobenzoates and ether-linked glycerobenzoates. The diacylglycerobenzoates were fractionated into molecular species by HPLC, quantitated, and counted for radioactivity. Label was incorporated into ROS phospholipids by day 1 and was followed up through the eighth day. The dipolyenoic species 22:6-22:6 from PC showed 1 3-5 times higher radiospecific activity than the same species from either PE or PS. The rate of decline was determined by calculating the half-life of each molecular species, which was used as a measure of the turnover of the species. The percent distribution of radioactivity in the molecular species of PC and PE was quite different from the relative mass distribution at day 1. However, percent dpm approached the mole percent by 31 days. In PS, percent dpm and mole percent were the same at all time points. These results indicate that the molecular species composition of PC and PE in frog retinal ROS is determined by a combination of factors, which include rate of synthesis, rate of degradation, and selective interconversions. In contrast, PS composition appears to be determined at the time of synthesis.
- Research Organization:
- Baylor College of Medicine, Houston, TX (USA)
- OSTI ID:
- 6245195
- Journal Information:
- Biochemistry; (United States), Vol. 27:25
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOLIPIDS
BIOSYNTHESIS
RETINA
BIOCHEMICAL REACTION KINETICS
TRITIUM COMPOUNDS
INJECTION
BENZOIC ACID
CELL MEMBRANES
FROGS
GLYCEROL
GLYCOLIPIDS
THIN-LAYER CHROMATOGRAPHY
ALCOHOLS
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BODY
BODY AREAS
CARBOHYDRATES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHROMATOGRAPHY
ESTERS
EYES
FACE
HEAD
HYDROXY COMPOUNDS
INTAKE
KINETICS
LABELLED COMPOUNDS
LIPIDS
MEMBRANES
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
REACTION KINETICS
SACCHARIDES
SENSE ORGANS
SEPARATION PROCESSES
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques