Silver stain for proteins in ultrathin polyacrylamide gels: a sensitive precipitation technique

A rapid and highly sensitive silver stain for visualization of proteins on ultrathin isoelectric focusing gels is described. This procedure is based on the specific interaction of silver and bromide ions in the presence of proteins and appears to involve a precipitation reaction. The technique requires only two reaction solutions, a silver nitrate and a potassium bromide solution. Silver consumption is very low because the silver nitrate solution is reusable. This procedure is well established for proteins separated by isoelectrofocusing in ultrathin gels.