A New Method of Visualization of the Enzymatic Activity of Flavocytochrome b 2 in Electrophoretograms

A new method of visualization of the activity of flavocytochrome b₂ (FCC b₂; L-lactate : ferricytochrome c oxidoreductase, EC 1.1.2.3) in electrophoretograms was developed based on the interaction between ferrocyanide (generated during the enzymatic reaction) and Fe³⁺, resulting in the formation of intensely colored precipitates of Berlin blue. The main advantages of this method were its high sensitivity (less than 0.005 U FCC b₂ was detected within a suitable time period) and the stability of the dye formed. The method developed can be used for determining FCC b₂ activity in cell-free extracts (e.g., in the selection of FCC b₂ producers) and monitoring chromatographic purification of proteins, as well as in other cases associated with FCC b₂ assessment.