Acyloxyacyl hydrolase

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acyloxyacyl hydrolase
5w78.jpg
Acyloxyacyl hydrolase heterodimer, Human
Identifiers
EC number 3.1.1.77
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / QuickGO

In enzymology, an acyloxyacyl hydrolase (EC 3.1.1.77) is an enzyme that catalyzes the chemical reaction

3-(acyloxy)acyl group of bacterial lipopolysaccharide (lipid A moiety) 3-hydroxyacyl group of bacterial lipopolysaccharide + a fatty acid

Hence, this enzyme has one substrate, the 3-(acyloxy)acyl groups of bacterial lipopolysaccharides, and two products, [partially deacylated lipopolysaccharide] and fatty acid.

The enzyme removes from lipid A the secondary acyl chains that are needed for lipopolysaccharides to be recognized by the MD-2--TLR4 receptor on animal cells. This reaction inactivates the lipopolysaccharide (endotoxin). Acyloxyacyl hydrolase is produced by monocyte-macrophages, neutrophils, dendritic cells, and renal cortical epithelial cells. It is a protein of Mr = ~60,000 that has two disulfide-linked subunits. The smaller subunit, of Mr = ~14,000 (including glycosylation), is a member of the SAPLIP (saposin-like protein) family along with amoebopore, granulysin, acid sphingomyelinase, surfactant protein B, and the 4 sphingolipid activator proteins (saposins). The larger subunit, Mr = 50,000, contains the active site serine and the other elements of the His-Asp-Ser triad; AOAH is a GDSL lipase that has activity toward certain glycerolipids in addition to its presumed major in vivo substrate, LPS.

References[edit]

  • Erwin AL, Munford RS (1990). "Deacylation of structurally diverse lipopolysaccharides by human acyloxyacyl hydrolase". J. Biol. Chem. 265 (27): 16444–9. PMID 2398058. 
  • Hagen, F.; O'Hara PJ, Munford RS; characterization of recombinant human acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides (1991). "Expression". Biochemistry. 30 (34): 8415–8423. doi:10.1021/bi00098a020. PMID 1883828. 
  • Munford RS, Hunter JP (1992). "Acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides, has phospholipase, lysophospholipase, diacylglycerollipase, and acyltransferase activities in vitro". J. Biol. Chem. 267 (14): 10116–21. PMID 1577781. 
  • Akoh CC, Lee GC, Shaw JF (2004). "GDSL family of serine esterases/lipases". Prog. Lipid. Res. 43: 534–552. doi:10.1016/j.plipres.2004.09.002. PMID 15522763.