Figure 14.

Effects of fluoroprolines on recombinant protein expression using the auxotrophic expression host Escherichia coli JM83. Left: sodium dodecyl sulfate–polyacrylamide gel electrophoresis expression profiles. Right: sequence compositions of corresponding proteins with marked single proline residues (orange) and oligoproline stretches (green). ni – non-induced (control) cell fraction, M – molecular weight (kDa) marker. A) Geobacillus thermoleovorans lipase (GTL) with 18 individual proline residues distributed throughout the protein sequence is expressed in the insoluble (inclusion bodies) form in the presence of S-Flp (Federica Agostini, unpublished results). B) In the presence of S-Flp in the growth medium, no expression of α-amylase from Pyrococcus woesei (PWA) could be detected (Michael Hoesl, unpublished results). Note, that in addition to 17 individual proline residues in the sequence, PWA also contains two additional oligoproline stretches. However, expressions in the presence of R-Flp yielded soluble and active variants for both enzymes.