Immunohistochemical localization of the acylases that catalyze the deacetylation of N-acetyl-L-cysteine and haloalkene-derived mercapturates

Acylases catalyze the hydrolysis of a range of S-substituted N-acetyl-L-cys teines. The hydrolysis of N-acetyl-L-cysteine is catalyzed by cytosolic acy lase I, and activity is present in human endothelial cells and rat lung, in testinal, and liver homogenates. Many haloalkenes are metabolized to mercap turates, which also undergo acylase-catalyzed hydrolysis. The acylases that catalyze the deacetylation of N-acetyl-L-cysteine and several haloalkene-d erived mercapturates have been recently identified: acylase I catalyzes the deacetylation of N-acetyl-L-cysteine and some haloalkene-derived mercaptur ates whereas an acylase purified from rat kidney cytosol catalyzes the deac etylation of a distinct set of substrates, including several haloalkene-der ived mercapturates. The objective of these studies was to examine the tissu e and subcellular localization of acylase I and purified rat kidney acylase . Immunoblotting showed the presence of immunoreactive acylase I and purifi ed rat kidney acylase in rat kidney, liver, lung, and brain. Both acylases were identified by immunohistochemistry in several rat organs, including ki dney, liver, lung, brain, stomach, intestines, adrenals, pancreas, and test is, indicating that acylase activity is widespread in rat tissues.