ExplorEnz: EC 3.1.1.77

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3.1.1.77

Accepted name:

acyloxyacyl hydrolase

Reaction:

3-(acyloxy)acyl group of bacterial toxin + H₂O = 3-hydroxyacyl group of bacterial toxin + a fatty acid

For diagram of reaction, 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 3.1.1.4 (phospholipase A₂), EC 3.1.1.5 (lysophospholipase), EC 3.1.1.32 (phospholipase A₁) and EC 3.1.1.52 (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, PDB, CAS registry number: 110277-64-0

References:

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]

[EC 3.1.1.77 created 2001]