Reaction: 3-(acyloxy)acyl group of bacterial toxin = 3-hydroxyacyl group of bacterial toxin + a fatty acid
For diagram click here.
Comments: The substrate is lipid A on the reducing end of the toxic lipopolysaccharide (LPS) of Salmonella typhimurium and related organisms. It consists of diglucosamine, β-D-GlcN-(1 6)-D-GlcN, attached by glycosylation on O-6 of its non-reducing residue, phosphorylated on O-4 of this residue and on O-1 of its potentially reducing residue. Both residues carry 3-(acyloxy)acyl groups on N-2 and O-3. The enzyme from human leucocytes detoxifies the lipid by hydrolysing the secondary acyl groups from O-3 of the 3-hydroxyacyl groups on the disaccharide (LPS). It also possesses a wide range of phospholipase and acyltransferase activities [e.g. EC 184.108.40.206 (phospholipase A2), EC 220.127.116.11 (lysophospholipase), EC 18.104.22.168 (phospholipase A1) and EC 22.214.171.124 (phosphatidylinositol deacylase)], hydrolysing diacylglycerol and phosphatidyl compounds, but not triacylglycerols. It has a preference for saturated C12-C16 acyl groups.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 110277-64-0
1. Erwin, A.L. and Munford, R.S. Deacylation of structurally diverse lipopolysaccharides by human acyloxyacyl hydrolase. J. Biol. Chem. 265 (1990) 16444-16449. [PMID: 2398058]
2. Hagen, F.S., Grant, F.J., Kuijper, J.L., Slaughter, C.A., Moomaw, C.R., Orth, K., O'Hara, P.J. and Munford, R.S. Expression and characterization of recombinant human acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides. Biochemistry 30 (1991) 8415-8423 [PMID: 1883828]
3. Munford, R.S. and Hunter, J.P. Acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides, has phospholipase, lysophospholipase, diacylglycerollipase, and acyltransferase activities in vitro. J. Biol. Chem. 267 (1992) 10116-10121. [PMID: 1577781]