A specific iron stain for iron-binding proteins in polyacrylamide gels: application to transferrin and lactoferrin

A new method for specifically staining the iron atoms present in transferrin and lactoferrin after polyacrylamide gel electrophoresis and isoelectric focusing is described. The stain, 3-(2-pyridyl)-5,6-bis(2-(5-furylsulfonic acid))-1,2,4-triazine, disodium salt, or Ferene S, will detect transferrin in 5 microliters of human serum, lactoferrin in 10 microliters of human whey, and 10 micrograms of purified primate (Macaca fascicularis) transferrin. This method of staining is very rapid as the serum transferrin bands can be seen within 5 to 10 min of staining.