Biosynthesis of an Elastin-Mimetic Polypeptide with Two Different Chemical Functional Groups within the Repetitive Elastin Fragment

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Junger, Andreas ; Kaufmann, Doris ; Scheibel, Thomas ; Weberskirch, Ralf:
Biosynthesis of an Elastin-Mimetic Polypeptide with Two Different Chemical Functional Groups within the Repetitive Elastin Fragment.
In: Macromolecular Bioscience. Bd. 5 (2005) Heft 6 . - S. 494-501.
ISSN 1616-5195
DOI: https://doi.org/10.1002/mabi.200400213

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Abstract

Summary: A new protein engineering strategy was utilized to synthesize an elastin-mimetic polypeptide. The primary structure represents an elastic motif composed of thirty amino acids with one lysine and one glutamic acid per repeat unit EMM = (VPGVG VPGKG VGPVG VPGVG VPGEG VPGIG). The gene was constructed using a Seamless Cloning method by generating three DNA cassettes which all encoded the EMM repeat unit, but with different flanking restriction recognition sites. The DNA cassettes were assembled to yield a gene that could be directly cloned into the multiple cloning site of pBluescript® II SK+. The resulting gene (EMM)7 with approximately 650 base pairs in length was further cloned into the expression vector pET-28b. Protein biosynthesis in E. coli strain BLR(DE3) resulted in the 21.5 kDa repeating polypeptide His6-(EMM)7 yielding up to 50 mg · L−1 of cell culture. Secondary structure analysis by far UV circular dichroism revealed a minimum at 197 nm and a shoulder at 218 nm indicative for a random coil with some type II β-turn conformation content. Lower critical solution temperature (LCST) behavior strongly depends on salt and polypeptide concentration. Importantly, first cross-linking experiments indicate successful hydrogel formation with a surface structure reminiscent to natural elastin as visualized by SEM micrographs.