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Phospholipases: Degradation of Phospholipids in Membranes and Emulsions

  1. Aron B Fisher1,
  2. Mehendra Jain2

Published Online: 15 DEC 2009

DOI: 10.1002/9780470015902.a0001394.pub2

eLS

eLS

How to Cite

Fisher, A. B. and Jain, M. 2009. Phospholipases: Degradation of Phospholipids in Membranes and Emulsions. eLS. .

Author Information

  1. 1

    University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA

  2. 2

    University of Delaware, Newark, Delaware, USA

Publication History

  1. Published Online: 15 DEC 2009

This is not the most recent version of the article. View current version (14 MAY 2015)

Abstract

Phospholipases are enzymes that degrade phospholipids through hydrolytic cleavage of carboxy- and phospho-diester bonds. The enzymes are classified as phospholipases A1, A2, C or D depending on the site of hydrolysis at the sn-1 or sn-2 acyl ester bond, at the glycerol phosphate bond or at the glycerol phosphate-base phosphodiester bond, respectively. Phospholipases A2 are secreted as components of snake and insect venoms, mammalian digestive juices and inflammatory exudates. Intracellular phospholipases participate in a broad spectrum of important physiological functions and pathophysiological processes through modification of phospholipids and generation of products that are potent regulators and messengers. These enzymes have evolved to hydrolyse phospholipids at an organized lipid–aqueous interface. Secreted phospholipase A2 can serve as a prototype for interfacial catalysis.

Key Concepts:

  • Phospholipases are hydrolytic enzymes that cleave at one of the four potential cleavage sites leading to the classification as phospholipase A1, A2, C or D.

  • These enzymes function at the interface with organized membranes and serve as models for interfacial catalysis.

  • Hydrolytic products of catalysis depending on the specific enzyme and substrate include free fatty acids, lysosphospholipids, diacylglycerol, phosphatidic acid and phosphorylated or free base (e.g. choline, ethanolamine, serine and inositol).

  • Secreted phospholipase A2 is an important component of snake and insect venoms, mammalian digestive fluids and inflammatory exudates where it leads to degradation of membranes and emulsified lipids.

  • Intracellular phospholipases have important roles in intracellular signalling through the generation of precursors of signalling molecules such as arachidonic acid, lysosphospholipids and inositol phosphates.

  • Intracellular phospholipase A2 activity generates the lysophospholipid substrate that is necessary for remodelling of cellular phospholipids by the deacylation–reacylation pathway.

  • Phospholipase activity inhibitors include specific agents that act directly on the enzyme and also agents that nonspecifically act by changing the organization of the interface or interfere with interfacial binding of the protein.

Keywords:

  • eiconsanoid synthesis;
  • pancreatic secretion;
  • snake venom;
  • cell signalling;
  • lipid remodeling;
  • interfacial enzymes