Purification of HSS from roots of S. vernalis. Indian ink stain of an SDS/PAGE on a 12% gel blotted onto a poly(vinylidene difluoride)-membrane. A 10-kDa protein ladder (Life Technologies, Grand Island, NY) (lane 1, the 50-kDa band is indicated by an arrow), crude extract (76.5 μg, lane 2), and the pooled fractions containing HSS activity of DEAE Fractogel (NaCl-elution, 9.5 μg, lane 3), Phenyl Sepharose (1.6 μg, lane 4), DEAE Fractogel (pH-elution, 1.5 μg, lane 5), spermidine-affinity chromatography and gel filtration (0.6 μg, lane 6), and Mono Q (0.6 μg, lane 7).