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Measuring the Elasticity of Poly‐ l ‐Proline Helices with Terahertz Spectroscopy
Author(s) -
Ruggiero Michael T.,
Sibik Juraj,
Orlando Roberto,
Zeitler J. Axel,
Korter Timothy M.
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201602268
Subject(s) - proline , elasticity (physics) , rigidity (electromagnetism) , chemistry , terahertz radiation , spectroscopy , crystallography , polymer , diffraction , terahertz spectroscopy and technology , materials science , physics , amino acid , optoelectronics , optics , organic chemistry , composite material , biochemistry , quantum mechanics
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.