An activity stain for proteins containing noncovalently bound flavin adenine dinucleotide.

A procedure has been developed to allow the visualization of FAD-containing proteins on polyacrylamide gels. The technique is based on the reconstitution of apo-D-amino acid oxidase with FAD and is thus specific for this cofactor. The stain is sensitive enough to detect 5 pmol of FAD and is therefore useful for the detection of flavoproteins in systems as complex as crude tissue or bacterial extracts.