Electrophoresis with the CleanGel system is a very gentle separation method for sensitive proteins and enzymes. This buffer kit is suitable for the analysis of proteins with cathodal migration at pH 5.5 e.g. proteins with pI >approx. pH 6.0. The buffer system has been optimized for washed, rehydratable dry gels. The amphoteric buffer compound HEPES (N-[2-hydroxyethyl]piperazine-N-[2-ethanesulfonic acid]), together with arginine and acetic acid, establishes a stable pH value of 5.5 in the gel.