title: Use of L-leucyl-3-carboxy-4-hydroxyanilide as substrate for determining the activity of microsomal aminopeptidase in serum.
abstract: We describe a colorimetric method for assay of microsomal aminopeptidase (EC 3.4.11.2) activity in serum. We use a new substrate, L-leucyl-3-carboxy-4-hydroxyanilide, p-xylenol as coupler, and sodium metaperiodate as oxidizing reagent. The colored substance formed by the oxidative condensation between p-xylenol and 5-aminosalicylic acid absorbs maximally at 635 nm, and can be directly measured in serum. In a previous method for this enzyme, L-leucyl-beta-naphthylamide was used as substrate and beta-naphthylamine, a carcinogenic reagent used as a standard in making the assay, was unsuitable for routine use. We found a close correlation between results obtained with the new, safer method and with the previous method.
authors.forename: M
authors.initials: M
authors.lastname: Shimamoto
authors.forename: S
authors.initials: S
authors.lastname: Takewaki
authors.forename: S
authors.initials: S
authors.lastname: Sakuraoka
authors.forename: T
authors.initials: T
authors.lastname: Nagasawa
authors.forename: K
authors.initials: K
authors.lastname: Kuroiwa
authors.forename: O
authors.initials: O
authors.lastname: Kodama
authors.forename: T
authors.initials: T
authors.lastname: Akatsuka
mesh_terms: D000626:Aminopeptidases / Q000097:blood*; D000636:Aminosalicylic Acids / Q000378:metabolism; D000813:Anilides; D001660:Biliary Tract Diseases / Q000175:diagnosis; D018826:CD13 Antigens; D002863:Chromogenic Compounds / Q000032:analysis; D004796:Clinical Enzyme Tests / Q000379:methods*; D003124:Colorimetry; D005260:Female; D006801:Humans; D007930:Leucine / Q000031:analogs & derivatives*; D008107:Liver Diseases / Q000175:diagnosis; D019804:Mesalamine; D011247:Pregnancy; D012995:Solubility; D013997:Time Factors; D014992:Xylenes / Q000378:metabolism
chemical_list: D000636:Aminosalicylic Acids; D000813:Anilides; D002863:Chromogenic Compounds; D014992:Xylenes; D019804:Mesalamine; C046671:leucyl-3-carboxy-4-hydroxyanilide; D000626:Aminopeptidases; D018826:CD13 Antigens; D007930:Leucine; C016834:3,5-xylenol