Glycerolipids brain

Ethanol and choline glycerolipids were isolated from calf brain and beef heart lipids by PTLC using silica gel H plates. Pure ethanol amine and choline plasmalogens were obtained with a yield of 80% [74]. Four phosphohpid components in the purple membrane (Bacteriorhodopsin) of Halobacterium halobium were isolated and identified by PTLC. Separated phosphohpids were add-hydrolyzed and further analyzed by GC. Silica gel G pates were used to fractionate alkylglycerol according to the number of carbon atoms in the aliphatic moiety [24]. Sterol esters, wax esters, free sterols, and polar lipids in dogskin hpids were separated by PTLC. The fatty acid composition of each group was determined by GC. 

Glycerolipids are derivatives of glycerol and fatty acids. Most brain glycerolipids are derivatives of phos-phatidic acid (PtdOH), which is diacylated sn-glycerol-3-phosphate. The notation sn refers to stereochemical... 

GC-MS has been responsible for the identification of a variety of unusual lipids associated with diseased conditions. Hydroxyocta-decadienoic esters of cholesterol for example, have been isolated from aortal atheroma placques [277] and branched chain and odd numbered fatty acids identified in the glycerolipids of brain, spinal cord and sciatic nerve [278] from a patient with methylmalonic aciduria. The latter compounds are thought to arise by the replacement of malonyl CoA with methyl malonyl CoA, and acetyl CoA with propionyl CoA at certain stages of fatty acid synthesis. In these and other examples, the lipids need to be hydrolysed to permit the identification of the constituent fatty acids. As the class of lipids is usually known from the separation procedure used, the nature of the fatty acids may allow the characterisation of the complete molecule. However, volatilisation of the intact lipid into the mass spectrometer when possible would be preferable, particularly when it is present in a mixture and separation of the components is first made by GC. 

Lin C-J, Peterson R, Eichberg J. The fatty acid composition of glycerolipids in nerve, brain and other tissues... 

Fluharty et aL (1974) have reported the isolation of S-labelled cerebroside sulphate. They injected the brains of young rats intracerebrally with [ S]-sulphate and sacrificed the animals 3 days later. Total lipids were extracted and glycerolipids destroyed by alkaline hydrolysis. TEAE-cellulose column chromatography was then used to purify the [ Sjsulphatide. Jatzkewitz and Nowoczek (1967) have synthesized o-galactose 3-sulphate and shown it to be identical to the galactose sulphate present in brain sulphatides. 

The fatty acid composition of toad brain and retina glycerolipids is comparatively presented in Fig. 1. The toad brain lipids, although being more unsaturated as expected for a poikilotherm, share the general features known to be present in mammalian brain high concentration of arachidonate in PI and PE, and of docosahexaenoate in PS,... 

Fig. 1. Fatty acid distribution in toad brain (0) and retina (0) glycerolipids.

Methylmalonyl-CoA may participate in fatty acid biosynthesis in place of malonyl-CoA, with the formation of methyl-branched long-chain (C17) fatty acids, and these acids have been isolated from glycerolipids of brain, spinal cord and sciatic nerve of a patient with methylmalonic aciduria and homo-cystinuria (Kishimoto et al., 1973). Odd-carbon-number straight-chain fatty acids (Ci5 and C17), due presumably to the accumulation of propionyl-CoA and the utilization of this substrate in fatty acid biosynthesis (Section 11.1), have also been observed in the central nervous system tissues of this patient (Kishimoto et aL, 1973), and another (the fourth described. Section 11.2.3) also with combined methylmalonic aciduria and homocystinuria (Dayan and Ramsay, 1974). It is relevant that methylmalonic acid may be utilized for the... 

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