Fig. 2.

Expression in vitro of multiple QconCATs. Twelve QconCAT genes, eleven of which had failed to express in vivo were selected. The coding regions was recovered by selective PCR amplification (panel A) and were expressed in vitro by cell-free synthesis in the presence of [¹³C₆][¹⁵N₄]arginine and [¹³C₆][¹⁵N₂] lysine and purified by a hexahistidine tag (panel B). The QconCATs were quantified by selected reaction monitoring using Glu-fibrinopeptide as standard (panel C), indicating typical yields of 250 pmol per reaction. Labeling of peptides was extremely efficient (panel D).