title: PAF-acetylhydrolases.
abstract: Platelet-activating factor acetylhydrolases (PAF-AHs, EC 3.1.1.47) constitute a unique subfamily of phospholipases A(2), specific for short acyl chains in the sn-2 position of the phospholipid. Their primary substrate is the platelet-activating factor, PAF, from which they cleave an acetyl moiety with concomitant release of lysoPAF. However, some acetylhydrolase will also hydrolyze other polar phospholipids with up to 6-carbons long acyl chains in the sn-2 position. PAF-acetylhydrolases are diverse enzymes, and the well-characterized isoforms are serine-dependent hydrolases, which do not require Ca(2+) for activity. Given the existence of two pools of PAF, intra- and extracellular, the acetylhydrolases can be divided into two subclasses: those found in the cytosol and enzymes secreted to blood plasma or other body fluids. Recent crystallographic studies shed new light on the complex structure-function relationships in PAF-AHs.
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, P.O. Box 10011, Charlottesville, VA 22906-0011, USA. zsd4n@virginia.edu
authors.forename: Z S
authors.initials: ZS
authors.lastname: Derewenda
authors.forename: Y S
authors.initials: YS
authors.lastname: Ho
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000818:Animals; D001921:Brain / Q000201:enzymology; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D010741:Phospholipases A / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase