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Enzymatic Mechanisms and Inhibition of Phospholipase A2

From Manoalide to the Lipocortins
  • Edward A. Dennis
  • Florence E. Davidson
  • Raymond A. Deems
Part of the New Horizons in Therapeutics book series (NHTH)

Abstract

The control of eicosanoid production in inflammatory and other cells depends on the release of free arachidonic acid from the sn-2 position of membrane phospholipids (summarized in Fig. 1). Phospholipase A2 is the simplest and most obvious candidate for the responsible enzyme, which makes its regulation, including both its activation and inhibition, crucial determinants of eicosanoid production (Dennis, 1987). Our laboratory has developed the dual phospholipid model (Roberts et al., 1977) to explain the mechanism of action of an extracellular phospholipase A2; our current understanding of the enzyme is summarized elsewhere (Dennis, 1983; Dennis and Plückthun, 1986). Our studies on the enzymes from snake venom and mammalian pancreas provide a paradigm for the phospholipases responsible for arachidonic acid release. In addition, they provide the best sources of readily available, pure, stable phospholipase A2 for testing potential inhibitors of phospholipase A2. This chapter discusses three inhibitor systems that we have recently characterized. These include amide ether analogues of phospholipids, which comprise an example of a reversible competitive inhibitor (Davidson et al, 1986), manoalide, which is an example of an irreversible inhibitor (Lom-bardo and Dennis, 1985) that is perhaps mechanism based and for which analogues can be studied (Deems et al.,1987), and the lipocortins or calpactins, where calpactin I is an example of inhibition by a substrate depletion model (Davidson et al., 1987). Meaningful interpretation of such studies can only be accomplished within the framework of the enzyme’s kinetics and mechanism of action at the lipid—water interface, which are discussed.

Keywords

Lactone Ring Enzymatic Mechanism Phospholipid Vesicle Arachidonic Acid Release Eicosanoid Production 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • Edward A. Dennis
    • 1
  • Florence E. Davidson
    • 1
  • Raymond A. Deems
    • 1
  1. 1.Department of ChemistryUniversity of CaliforniaSan Diego, La JollaUSA

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