Glycerol enzymatic acylation

Bertrams, M. and Heinz, E. (1976) Experiments on enzymatic acylation of sn-glycerol 3-phosphate with enzyme preparations from pea and spinach leaves. Planta 132, 161-168. 

The other phospholipids can be derived from phosphatidates (residue = phosphatidyl). Their phosphate residues are esterified with the hydroxyl group of an amino alcohol choline, ethanolamine, or serine) or with the cyclohexane derivative myo-inositol. Phosphatidylcholine is shown here as an example of this type of compound. When two phosphatidyl residues are linked with one glycerol, the result is cardiolipin (not shown), a phospholipid that is characteristic of the inner mitochondrial membrane. Lysophospholipids arise from phospholipids by enzymatic cleavage of an acyl residue. The hemolytic effect of bee and snake venoms is due in part to this reaction. 

In addition to de novo synthesis from acetyl CoA, fatty acids can be derived from the enzymatic hydrolysis of triglycerides. The primary form in which fatty acids are stored and transported between cells, triglycerides consist of three fatty acyl chains esterified to glycerol hence they are also called triacylglycerols (see Figure 18-2). Complete hydrolysis of a triglyceride molecule yields three unesterified fatty acid molecules, or free fatty acids (FFAs), and a glycerol molecule. 

LPA can be produced by several enzymatic routes (Figure 4). However, the relative contributions of these to LPA production is not known since specific inhibitors for many of the enzymes involved are not available (Pages et al., 2001). Firstly, de novo biosynthesis of LPA occurs by acylation of glycerol 3-phosphate, catalysed by glycerophosphate acyltransferase, in both the endoplasmic reticulum and mitochondria. Alternatively, LPA can be synthesized by the phosphorylation of monoacylglycerol or, in peroxisomes, by the reduction of acyl dihydroxyacetone phosphate. Subsequently, acylation of LPA by monoacylglycerolphosphate acyltransferase produces the precursor of all glycerophospholipids, phosphatidic acid. The latter can also act as a precursor of LPA synthesis by phospholipase A-catalysed deacylation. 

Cell suspension cultures of soya were incubated with mixtures of positional and geometrical isomers of [l- C]octadecenoic acids in order to determine enzymatic specificities for the incorporation of individual isomeric fatty acids into the glycerolipids, for instance triacylglycerols [60]. It is obvious from the data given in Table 3 that A9 isomers of both mixed substrates, (Z)-and f J-octadecenoic acids, are preferentially incorporated into the sn-2 position of the glycerol backbone, whereas a much lower percentage of these acyl moieties are esterified to the... 

The enzymatic synthesis of [ C]18 1-ACP Isoforms was according to a published procedure (9), and was purified through the octyl sepharose step. Oleoyl-ACP thloesterase was partially purified from spinach tissue by methods which Involved acid precipitation and either Ion-exchange or affinity chromatography (7,8). Glycerol-3-phosphate acyl transferase was purified by ammonium sulfate fractionation, DEAE and... 

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