A convenient and highly sensitive spectrophotometric assay for tryptophan 2,3-dioxygenase

✍ Scribed by Heribert Metzler; Rolf Gebhardt; Walter Oberrauch; Dieter Mecke

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 528 KB
• Volume: 121
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(82)90550-4

✦ Synopsis

A highly sensitive assay for tryptophan dioxygenase based on the formation of an azo-dye derivative of kynurenine is described combining simplicity and excellent reproducibility. The assay procedure provides optimal conditions for enzyme activation, diazotization of kynurenine, and color development. Furthermore, it renders the measurement of tryptophan dioxygenase activity independent of formamidase, in contrast to many other methods reported, which thus may lead to misinterpretations, if no additional precautions against rate limitation of that enzyme are taken. These improvements make the assay particularly suited for small samples of any tissue, irrespective of endogenous formamidase activity, as well as for more purified enzyme preparations, even at very low activities.