Phospholipases plant

Phospholipase D is widely distributed in bacteria, fungi, plants and animals, and is present in almost all mammalian cells [3]. In mammals, it occurs as alternatively spliced products of two genes (PLD1 andPLD2) (Fig. 3). Most mammalian cells express different levels of both isoforms. Both PLD1 and PLD2 have four conserved sequences (I-IV), and sequences I and IV contain the HXKX4D (HKD) motif that is characteristic of the PLD superfamily, which includes bacterial endonucleases, phospholipid synthases, viral envelope... 

Encompassing approx 6000 medicinal plant species, the medicinal flora of Asia and the Pacific comprise a fantastic source of pharmacologically active products, and the number of plant species principally used for the treatment of inflammation can be estimated to be more that 380. This chapter will focus on the potentials of medicinal plants of Asia as a source of original anti-inflammatory drugs, with particular interest payed to inhibitors of phospholipase A2, COX, lipoxygenases, elastase, and NOS. 

Other medicinal features to consider when searching for plants with potential as phospholipases A2 are abortifacient, analgesic, antipyretic, and hypoglycemic uses. Such features are present in the following plant species. 

DC 196 Kleinig, H., and C. Kopp. Lipids, lipid DC208 turnover, and phospholipase D in plant suspension culture cells (Daucus carota). Planta 1978 139(1) 61-65. 

Welti, R., Li, W., Li, M., Sang, Y., Biesiada, H., Zhou, H. -E., Rajashekar, C. B., Williams, T. D., Wang, X. (2002). Profiling membrane lipids in plant stress responses. Role of phospholipase Da in freezing-induced lipid changes in Arabidopsis. Journal of Biological Chemistry, 277,31994-32002. 

Plants also derive important signaling molecules from fatty acids. As in animals, a key step in the initiation of signaling involves activation of a specific phospholipase. In plants, the fatty acid substrate that is re-... 

Further support for the hypothesis that Ca2+ plays a central role in regulating phytoalexin accumulation is provided by experiments in which the turnover of phosphatidylinositol was measured in the plasma membrane of elicitor-treated carrot cells [17]. The carrot cells were first labelled with [3H]myo-inositol and, after the addition of elicitors, acid extracts of the cells were analyzed chromatographically for the production of inositol trisphosphate (IP3). In cells treated with elicitor, the release of radioactive IP3 increased with time and attained a maximum at 3 - 5 min after treatment. Phospholipase activity responsible for the degradation of phosphorylated phosphatidylinositol increased correspondingly. Several reports have shown that IP3 induces rapid release of Ca2+ from intracellular stores in animal cells [18, 19]. Studies on plant cells have also demonstrated that exogenous IP3 releases Ca2+ from microsomal preparations at micromolar concentrations, although only limited... 

Russell, L., Stokes, A. R., Macdonald, H., Muscolo, A., and Nardi, S. (2006). Stomatal responses to humic substances and auxin are sensitive to inhibitors of phospholipase A2. Plant Soil 283,175-185. 

Scherer, G. F. E., and Andre, B. (1989). A rapid response to a plant hormone Auxin stimulates phospholipase A2 in vivo and in vitro. Biochem. Biophys. Res. Commun. 163,111-117. 

Proof for the existence of phospholipase D in nature (i.e., in plant tissues) was provided by Hanahan and Chaikoff (1947). Subsequently, this enzyme has been detected in microorganism and mammalian cells. An overall, in-depth treatment on phospholipase D is given by Waite (1987). 

Phosphodiesterase (Hydrolysis) Activity. A rather broad substrate specificity is exhibited by the purified phospholipase D (phosphodiesterase activity). It can attack phosphatidylcholine, phosphatidylethanolamine, phospha-tidylserine, and phosphatidylglycerol. In most cases, Ca2+ was an activator, but variable results were obtained on the positive influence of diethyl ether on the catalytic activity of different sources of this enzyme. Usually the optimum pH was in the range from 5.0 to 7.0. Mammalian phospholipase D, containing both the phosphodiesterase and transphosphatidylase activities, exhibited a broad-range substrate specificity similar to that of the plant enzyme. However, the mammalian enzyme showed a dependency for the presence of oleic acid in the reaction system (Kobayashi and Kanfer, 1991). 

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