Measuring the Elasticity of Poly-l-Proline Helices with Terahertz Spectroscopy.
The rigidity of poly-l-proline is an important contributor to the stability of many protein secondary structures, where it has been shown to strongly influence bulk flexibility. The experimental Young's moduli of two known poly-l-proline helical forms, right-handed all-cis (Form I) and left-handed all-trans (Form II), were determined in the crystalline state by using an approach that combines terahertz time-domain spectroscopy, X-ray diffraction, and solid-state density functional theory. Contrary to expectations, the helices were found to be considerably less rigid than many other natural and synthetic polymers, as well as differing greatly from each other, with Young's moduli of 4.9 and 9.6 GPa for Forms I and II, respectively.
Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, Syracuse, NY, 13244-4100, USA.
Michael T
MT
Ruggiero
Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge, CB2 3RA, UK.|F. Hoffmann-La Roche AG, Konzern-Hauptsitz, Grenzacherstrasse 124, 4070, Basel, Switzerland.
Juraj
J
Sibik
Dipartimento di Chimica and Centre of Excellence Nanostructured Interfaces and Surfaces, Università di Torino, via Giuria 5, 10125, Torino, Italy.
Roberto
R
Orlando
Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge, CB2 3RA, UK.
J Axel
JA
Zeitler
Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, Syracuse, NY, 13244-4100, USA. tmkorter@syr.edu.
Timothy M
TM
Korter
biopolymers; elasticity; polyproline; proteins; terahertz spectroscopy