Deformation responses of a physically cross-linked high molecular weight elastin-like protein polymer.
Recombinant protein polymers were synthesized and examined under various loading conditions to assess the mechanical stability and deformation responses of physically cross-linked, hydrated, protein polymer networks designed as triblock copolymers with central elastomeric and flanking plastic-like blocks. Uniaxial stress-strain properties, creep and stress relaxation behavior, as well as the effect of various mechanical preconditioning protocols on these responses were characterized. Significantly, we demonstrate for the first time that ABA triblock protein copolymers when redesigned with substantially larger endblock segments can withstand significantly greater loads. Furthermore, the presence of three distinct phases of deformation behavior was revealed upon subjecting physically cross-linked protein networks to step and cyclic loading protocols in which the magnitude of the imposed stress was incrementally increased over time. We speculate that these phases correspond to the stretch of polypeptide bonds, the conformational changes of polypeptide chains, and the disruption of physical cross-links. The capacity to select a genetically engineered protein polymer that is suitable for its intended application requires an appreciation of its viscoelastic characteristics and the capacity of both molecular structure and conditioning protocols to influence these properties.
Wu
Xiaoyi
X
Department of Surgery, Emory University, Atlanta, Georgia 30332, USA.
Sallach
Rory E
RE
Caves
Jeffrey M
JM
Conticello
Vincent P
VP
Chaikof
Elliot L
EL
D003432:Cross-Linking Reagents; D004548:Elasticity; D020724:Elastomers; D019563:Mechanics; D020815:Polyproteins / Q000138:chemical synthesis*; D011487:Protein Conformation; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000138:chemical synthesis
D003432:Cross-Linking Reagents; D020724:Elastomers; D020815:Polyproteins; D011994:Recombinant Proteins