Comparison of His-tag and GST-tag purification. A set of proteins were expressed with N-terminal His-GST-tag in 1 ml cultures in 96-deep well microplates. Recombinant proteins were purified using either Ni-NTA-agarose or glutathione agarose. The Coomassie-stained SDS-PAGE shows the expression products of 15 different proteins purified on the pipetting robot. Numbers in the upper panel indicate the expression clones. The lanes of the lower panel correspond to the upper panel. The first lane per clone represents the whole cellular extract and the second lane the purified protein. Expression clones of two different transformants resulting from the same expression construct are represented by annotations a and b, respectively. M = molecular weight standard, kDa.