title: A fluorescent probe for the active site of bovine trypsin.
abstract: The compound 2-p-toluidinylnaphthalene-6-(N-beta-ethylamine hydrochloride) sulfonamide (compound III) has a structure that is appropriate for binding to the active site of trypsin. It also has the property of fluorescence when in a nonpolar environment such as when bound to trypsin. Kinetic studies show that compound III competitively inhibits the trypsin-catalyzed hydrolysis of L-alpha-N-Benzoylarginine-p-nitroanilide (L-BAPNA) with a KI' of 3.6 X 10(-4)M at pH 8.1. The fluorescence enhancement of III when bound to bovine trypsin further confirms the existence of a hydrophobic specificity region within the active site of trypsin. The pH dependence of the fluorescence of compound III with trypsin was also determined.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002863:Chromogenic Compounds / Q000378:metabolism; D005456:Fluorescent Dyes / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013050:Spectrometry, Fluorescence; D014052:Toluidines / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism*
chemical_list: D002863:Chromogenic Compounds; D005456:Fluorescent Dyes; D014052:Toluidines; C041061:2-4-toluidinylnaphthalene-6-(N-beta-ethylamine)sulfonamide; D014357:Trypsin