ABSTRACT
Proteins exhibit precisely dened sequences, exact biochemical compositions, and a dazzling array of complex conformational structures. Compared to their synthetic polymer analogs, which generally result in a statistical distribution of macromolecules with varied sequence, composition, and conformation, proteins are designed and produced as exactly specied macromolecules. This ability to design macromolecules with molecular-level precision can be exploited to engineer protein-based materials with unique properties. While the physical rules that govern protein folding into specic conformations and further self-assembly into hierarchical structures are still being elucidated, much has been learned already by mimicking protein sequences that are commonly found in nature to create new protein-based materials. Although this strategy was rst widely described about two decades ago, the diversity of potential amino-acid sequences and range of promising materials applications are only just beginning to be explored more broadly. This chapter will give a brief historical overview of the eld, present several case studies of interesting
Motivation .............................................................................................................. 179 Historical Perspective ............................................................................................ 180 Design Strategy ...................................................................................................... 182 Case Studies ........................................................................................................... 184
Elastin Motifs .................................................................................................... 184 Silk Motifs ......................................................................................................... 185 Coiled-Coil Motifs ............................................................................................ 186 Calmodulin Motifs ............................................................................................ 187
Current and Future Challenges .............................................................................. 189 Expanding the Library of Peptide Modules ...................................................... 189 Optimization of Cost-Efcient Synthesis .......................................................... 192 Immunogenicity ................................................................................................ 193 Dynamic and Adaptive Materials ...................................................................... 194 Hierarchical Assembly ...................................................................................... 196
References .............................................................................................................. 196
and important engineered protein-based biomaterials, and provide an introduction to some of the current challenges and exciting directions the eld is beginning to investigate. The chapter will be limited to materials synthesized from engineered recombinant proteins, as several excellent reviews exist on synthetic peptide-based materials (Holmes 2002, Woolfson and Ryadnov 2006).
