High resolution ultrathin‐layer isoelectric focusing of PGM1‐subgroups in forensic blood typing

Abstract
Ultrathin‐layer isoelectric focusing in 100 um polyacrylamide gels is described for the separation of the isozymes of the PGM1‐locus. The PGM1‐subgroups are best resolved in pH 5–7 gradients obtained by mixing Ampholine and Servalyt carrier ampholytes in a 2:1 ratio. By using a high field strength (180 V/cm) in the final stage of isoelectric focusing, the isozyme bands are sharper than in conventional thin‐layer gels. This facilitates identification of the subgroups. Distortions of the pH gradient are avoided if low initial field strengths (15–20 V/cm) are used. The method is highly reproducible and equally applicable for the analysis of blood samples as well as blood stains.