Acyloxyacyl Hydrolase (AOAH)

Acyloxyacyl hydrolase (AOAH) is a 2-subunit lipase present in phagocytic cells. This enzyme specifically hydrolyzes the secondary acyl chains of the lipopolysaccharide found in the walls of gram-negative bacteria. Although the physiologic function of AOAH has not been clearly defined, its action on lipopolysaccharide (or endotoxin) suggests that it modulates the host's inflammatory response to gram-negative bacteria. This hypothesis is supported by studies showing that the deacylation of lipopolysaccharide by AOAH in vitro greatly reduces its toxicity and activity. Hagen et al. (1991) cloned and characterized cDNA for human AOAH and showed that its 2 subunits are translated from a single mRNA molecule about 2.2 kb long. By fluorescence in situ hybridization, Whitmore et al. (1994) mapped the AOAH gene to 7p14-p12.