Intracellular electron donor stripping to identify electron donors of indigo reduction

The identification of the electron donor of a reduction reaction is one of the most important points for revealing the reaction mechanism and the enzyme involved. In some cases, it is difficult to identify the electron donor because microbial cells have sufficient quantities of electron donors in the cells. In this study, we found that potassium hexacyanoferrate (Ⅲ) is a good stripping chemical compound of intracellular electron donors. Ethanol and glucose clearly enhanced the indigo-reducing activity of the microbial cells after stripping. This supports our previous proposal that acetaldehyde is an electron donor for the reduction of methyl viologen as a representative of indigo. We constructed the stripping of intracellular electron donors for the first time as a useful technique for identifying the electron donor of a reduction reaction when microorganisms have sufficient electron donors in their cells.