Related Experiment Video
Updated: Mar 22, 2026

DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers
Published on: October 25, 2017
Measuring the Elasticity of Poly-l-Proline Helices with Terahertz Spectroscopy
Michael T Ruggiero1, Juraj Sibik2,3, Roberto Orlando4
1Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, Syracuse, NY, 13244-4100, USA.
Abstract:
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.
Related Concept Videos
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
¹H NMR of Labile Protons: Temporal Resolution
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...

