Phospholipid catabolism

Investigation of phospholipid catabolic and anabolic enzymes revealed lower activity of PLA2 and phosphoethanolamine- and phosphocholine-cytidylyltransferases in autopsied substantia nigra of patients with idiopathic Parkinson s disease. The decreased rate of phospholipid turnover in the pigmented neurons of the substantia nigra might result in reduced ability to repair oxidative membrane damage and thus accumulation of OxPL in Parkinson s disease (Ross et al. 2001). 

Blusztajn, J.K., Gonzalez-Coviella, I.L., Logue, M., Growdon, J.H. and Wurtman, R.J. (1990) Levels of phospholipid catabolic intermediates, glycerophosphocholine and glycero-phosphoethanolamine, are elevated in brains of Alzheimer s disease but not of Down s syndrome patients. Brain Res. 536 240-244. 

Several observations support the contention that cytosolic lipid-protein particles originate from membranes. In particular, they contain phospholipid with the same fatty acids, albeit in different proportions, found in phospholipid of corresponding microsomal membranes [3]. In addition, lipid-protein particles with essentially similar properties can be generated in vitro from isolated microsomal membranes under conditions in which phospholipid catabolism has been activated by the addition of Ca [2,3]. The finding that the particles contain high concentrations of free fatly acids and steryl and wax esters suggests that they are formed at specific... 

Leshen, Y. 1987. Membrane phospholipid catabolism and Ca activity in control c senescence. Physiol. Plant 69, 551-59. 

In higher plants, the lipolytic enzymes and their physiological functions are not well characterized [1]. iMost reports demonstrated that phospholipid catabolism in plants is achieved by the concerted actions of membrane-bound enzymes including phospholipase D, phosphatidate phosphatase, lipolytic acyl hydrolases and lipoxygenases [1,2]. With the exception of the phospholipase D, the literature on plant phospholipases is still very limited. We previously reported that tonoplast from Acer pseudoplatanus cells contains small amounts of phosphatidic acid and lysophospholipids, which were produced together with free fatty acids, particularly after addition of Ca " [31. These data suggested the possible involvement of phospholipase D and phospholipase A in the metabolism of vacuolar membrane lipids. The phospholipase activities were studied by following the hydrolysis of added sn-2-[14c]linoleyl-PC to tonoplast vesicles. Tonoplast was obtained by osmotic lysis of pure preparations of vacuoles isolated from protoplasts derived from Acer pseudoplatanus cells [4]. This present work demonstrated clearly the presence of phospholipase D and phospholipase Ai activities associated with the tonoplast of Acer, The phospholipase Ai showed an optimal activity at pH about 6-6.5, did not necessarily require divalent cations, but was stimulated by Mg- and particularly by Ca. This work presents the first evidence for the presence of phospholipases A in plant cells. 

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