Sensitive colorimetric assay of serum diamine oxidase

Kenji Takagi, Makoto Nakao, Yozo Ogura, Toshitaka Nabeshima, Akira Kunii

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91 Citations (Scopus)


A simple and sensitive colorimetric assay for serum diamine oxidase (DAO) activity was based on a coupled reaction with peroxidase and a new chromogen, 10-(carboxymethyl-aminocarbonyl)-3,7-bis(dimethylamino) phenothiazine sodium salt (DA-67). In the presence of peroxide and DA-67, peroxidase catalyzes the formation of methylene blue having an absorption maximum at 668 nm. The proposed method eliminates the interferences occurring in serum with use of ascorbate oxidase and stops the reaction with sodium diethyldithiocarbamate, leaving the methylene blue in the reaction mixture stable for about 2 h. Low normal basal values of serum DAO can be determined in the range 2.8-9.0 units/l. Since all reagents are commercially available the method is suitable for the clinical laboratory.

Original languageEnglish
Pages (from-to)67-75
Number of pages9
JournalClinica Chimica Acta
Issue number1
Publication statusPublished - 04-1994
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Clinical Biochemistry
  • Biochemistry, medical


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