3. Results
3.1. Biosynthesis of silk protein and chimeras
The strategy for biosynthesis of silk protein and the chimeras
was adopted as described previously [10,22]. The constructs of
the 6mer or the chimeras (6mer-A1, A3 or R5) are illustrated in
Fig. 1A. NheI-SpeI digestion and DNA sequencing confirmed the
inserts. SDS-PAGE indicated both expression and purification of
the 6mer and the chimeras were successful, and no obvious impurities
were detected on the gels (Fig. 1B). The MW of each protein
identified by mass spectroscopy matched the target calculation
(Fig. 1C), indicating the expressed and the purified proteins were
correctly generated. In the case of the 6mer, the molecular weight
was above 28 kDa on the gels, but was identified at 21–23 kDa by
mass spectroscopy. This discrepancy has been reported previously
for repetitive silk-based copolymers and likely reflects the hydrophobic
nature and repetitive features in the proteins [10,27,28].