posted on 2005-05-09, 00:00authored byRobin S. Farmer, Kristi L. Kiick
The synthesis of protein-based polymers with controlled conformational properties and functional group
placement offers many opportunities for the design of advanced materials. In this work, protein engineering
methods have been used to produce repetitive alanine-rich protein polymers with the sequence [(AAAQ)5(AAAE)(AAAQ)5]x (x = 2 and 6); these macromolecules may mimic architectural features of certain alanine-rich helical sequences found in natural proteins. Various proteins from this family can be readily expressed
and purified from Escherichia coli. Circular dichroic spectroscopy (CD) characterization demonstrates that
the purified proteins are highly helical under a variety of conditions. Thermal analysis of [(AAAQ)5(AAAE)(AAAQ)5]2 via differential scanning calorimetry (DSC) and CD indicates that the protein undergoes a
reversible helix−coil transition at approximately 45 °C and that the protein conformation can be manipulated
at elevated temperatures depending on solution conditions. The demonstrated conformational properties of
these artificial proteins suggest that they may be excellent candidates for elucidating structure−function
relationships in biopolymers for nanotechnology and biological applications.