A representative hisMBP-DHDPSL size-exclusion chromatogram and the accompanying SDS–PAGE gel (inset). The red line indicates the fractions (2 ml each) analysed by SDS–PAGE. The fractions indicated by the triangles at the top of the gel were retained for later experiments including crystallization. The sample intended for the empty lane indicated by the orange triangle was not loaded. A HiLoad Superdex 16/60 200 preparative-grade size-exclusion column (GE Healthcare) was used for this purification.