Acyloxyacyl hydrolase

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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) $\rightleftharpoons$ 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.

This enzyme belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name of this enzyme class is '.

[edit] References

IUBMB entry for 3.1.1.77
BRENDA references for 3.1.1.77 (Recommended.)
PubMed references for 3.1.1.77
PubMed Central references for 3.1.1.77
Google Scholar references for 3.1.1.77
Erwin AL, Munford RS (1990). "Deacylation of structurally diverse lipopolysaccharides by human acyloxyacyl hydrolase". J. Biol. Chem. 265: 16444–9. PMID 2398058.
Hagen, F., O'Hara PJ, Munford RS (1991). "Expression and characterization of recombinant human acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides". Biochemistry. 30: 8415–23. 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: 10116–21. PMID 1577781.