Chelating Chromogenic Substrates

In recent years chromogenic substrates have been developed that rely on a chelate forming, after enzymatic hydrolysis, between the free chromogen and a metal iron, typically Fe3+. Chelating enzyme substrates are available with non-diffuse end-points, the chromogens 8-Hydroxyquinoline 8HQ (product code 35XXX), Alizarin (product code 89XXX) and the more soluble alizarin sodium salt (product code 51XXX), 3,4-Cyclohexenoesculetin CHE (product code 75XXX) and 6,7-Dibromo-2,3-Dihydroxynaphthalene or Brown substrates (product code 56XXX) all offer an insoluble endpoint, and are therefore best suited for use in solid media. Whereas 2,3-Dihydroxynaphthalene or DHN (product code 80XXX) and catechol (14XXX) substrates both give a soluble endpoint thus ideally suited to applications in liquid media. These substrates offer the advantage over indoxyl based enzyme substrates in that they can be used in the absence of oxygen.