In some species minor cross reactions with some larger proteins are seen. These may contain related iron-sulfur binding motifs. Therefore size verification of the reacting band is required. Due to the small size of the protein, care should be taken to differentiate between chemiluminescent signal from PsaC and non-specific signals from chlotophylls or lipids if pigment is retained near the bottom of the blot.Protein standard: use a load of 2 l per well with ECL detection system and 4 l per well with alkaline phospatase.