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BP: Fachverband Biologische Physik
BP 30: Biomaterials and Biopolymers I (joint CPP/BP)
BP 30.9: Talk
Wednesday, April 2, 2014, 17:30–17:45, ZEU 222
Thermal Melting of Protein Beta Sheet Crystals — Andreas Wurm1, Evgeny Zhuravlev1, Xiao Hu2, David Kaplan2, Peggy Cebe2, and •Christoph Schick1 — 1University of Rostock, Institute of Physics, Germany — 2Tufts University, Medford MA, USA
The remarkable stability that makes silk useful in garments and surgical sutures has impeded efforts by scientists to study its thermo-physical properties. Here, we use fast scanning chip calorimetry and report the first reversible thermal melting of protein beta-pleated-sheet crystals, exemplified by silk fibroin. Heating nanogram-sized samples at 2000K/s, allowed us to avoid thermal decomposition, and demonstrate that beta-pleated-sheet crystals melt to become random coils, helices and turns. We establish that following melting silk can be recrystallized into beta-pleated-sheets, and remelted. The similarity between thermal melting behavior of beta-pleated-sheet crystals and crystals of synthetic polymers is confirmed. Significance for controlling beta-pleated-sheet content during thermal processing of biomaterials is envisioned based on these findings. Demonstration of reversible thermal transitions in silk, the most beta-pleated-sheet-enriched and stable protein, suggests important new insights can also be gained with the broader range of proteins where beta-pleated-sheets serve as critical control points in structural transitions.