Vol. 28, Issue 6, 625-632, June 2000

Immunohistochemical Localization of the Acylases that Catalyze the Deacetylation of N-Acetyl-L-cysteine and Haloalkene-Derived Mercapturates

Vinita Uttamsingh,¹ Raymond B. Baggs, Daria M. Krenitsky, and M. W. Anders

Departments of Pharmacology and Physiology (V.U., D.M.K., M.W.A.) and Laboratory Animal Medicine (R.B.B.), University of Rochester Medical Center, Rochester, New York

Acylases catalyze the hydrolysis of a range of S-substituted N-acetyl-L-cysteines. The hydrolysis of N-acetyl-L-cysteine is catalyzed by cytosolic acylase I, and activity is present in human endothelial cells and rat lung, intestinal, and liver homogenates. Many haloalkenes are metabolized to mercapturates, which also undergo acylase-catalyzed hydrolysis. The acylases that catalyze the deacetylation of N-acetyl-L-cysteine and several haloalkene-derived mercapturates have been recently identified: acylase I catalyzes the deacetylation of N-acetyl-L-cysteine and some haloalkene-derived mercapturates whereas an acylase purified from rat kidney cytosol catalyzes the deacetylation of a distinct set of substrates, including several haloalkene-derived mercapturates. The objective of these studies was to examine the tissue and subcellular localization of acylase I and purified rat kidney acylase. Immunoblotting showed the presence of immunoreactive acylase I and purified rat kidney acylase in rat kidney, liver, lung, and brain. Both acylases were identified by immunohistochemistry in several rat organs, including kidney, liver, lung, brain, stomach, intestines, adrenals, pancreas, and testis, indicating that acylase activity is widespread in rat tissues.