Resistance of affinity tags to disrupting agents. (A) Coomassie-stained gels showing retention of the three-helical SNARE proteins on syntaxin beads following washes with the indicated eluants. (B) A bar chart showing residual amouts of the S-B protein on the syntaxin Biacore chip following application of indicated solutions. The signals were normalized to the original bound S-B protein after the surface plasmon resonance experiment. The data show mean +/- standard deviation, n = 3. (C) Coomassie-stained gels showing retention of biotinilated GST-SNAP25, His-tag SNAP25 and GST-tag SNAP25 on streptavidin, Ni-NTA and glutathione beads respectively following washes with the indicated eluants.