SDS-PAGE of samples from the purification of Nocardia GTPCH. Lane 1, crude extract; lane 2, dialyzed ammonium sulfate precipitate; lane 3, pooled fractions from GTP-agarose; lane 4, pooled fractions from DEAE Sepharose; lane 5, pooled fractions from Ultragel AcA 34; lane 6, control with sample buffer; lane 7, molecular mass markers (phosphorylase b [97.4 kDa], serum albumin [66.2 kDa], ovalbumin [45 kDa], carbonic anhydrase [31 kDa], trypsin inhibitor [21.5 kDa], and lysozyme [14.4 kDa]).