title: N-ethylmaleimide inhibits xanthine oxidase activity with no detectable change in xanthine dehydrogenase activity in rabbit liver.
abstract: The effect of an alkylating agent, N-ethylmaleimide (NEM), on the activities of xanthine oxidase (XO) and xanthine dehydrogenase (XD) in the presence and absence of Cu2+ or trypsin in the cytosolic fraction from rabbit liver was examined. At concentrations ranging from 0.25 to 2.0 microM, allopurinol, which is generally considered to be a XO inhibitor, suppressed the XD activity (41.5-93.4% inhibition) in addition to the XO activity (28.6-88.4% inhibition) under basal conditions, without the addition of Cu2+ or trypsin. In contrast, NEM (100-400 microM) inhibited the XO activity (35.7-85.7% inhibition) without affecting the XD activity. Also, NEM inhibited the Cu2+- and trypsin-induced XO activities, but did not affect the XD activity at the same concentration range. These results demonstrate that NEM can be a selective inhibitor of XO activity in rabbit liver.
authors.affiliation: Department of Hygienic Chemistry, Osaka University of Pharmaceutical Sciences, Takatsuki, Japan. fujimoto@oysun01.oups.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: S
authors.initials: S
authors.lastname: Sakuma
authors.forename: T
authors.initials: T
authors.lastname: Tagami
authors.forename: R
authors.initials: R
authors.lastname: Ichikawa
authors.forename: T
authors.initials: T
authors.lastname: Fujita
mesh_terms: D000493:Allopurinol / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D005033:Ethylmaleimide / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D011817:Rabbits; D014357:Trypsin / Q000378:metabolism; D014968:Xanthine Dehydrogenase / Q000378:metabolism*; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors*
chemical_list: D000493:Allopurinol; D014968:Xanthine Dehydrogenase; D014969:Xanthine Oxidase; D014357:Trypsin; D005033:Ethylmaleimide; D002118:Calcium