Periplasmic export of scFvs and signal peptide cleavage. A.) Western-blot of purified antibodies extracted from whole cells (WCE) and periplasmic preparations (PPP) and chromogenic detection of the Strep-tag® II at the C-terminus. A minor fraction of incomplete N-terminal processing (cleavage of the 22 amino acid pelB-leader sequence) is visible only in the case of HT186-D11 whole cell extracts (arrows). B.) N-terminal sequencing by Edman degradation confirmed the predicted cleavage sites following the A-M-A motif. X, amino acid position with ambiguous identification.