Since its discovery in 1945 by Bloch and Purcell, nuclear magnetic resonance, NMR, served as one of the most important tools for chemists. This presentation will describe two examples that make use of NMR to understand the behavior of polypeptides. Self-diffusion of poly(γ-stearyl-L-glutamate), PSLG, as a function of molecular weight, M, and concentration was studied by pulsed gradient spin echo (PGSE). The self-diffusion coefficient significantly decreased with increased concentration for the medium range of molecular weight while an unexpectedly weak decrease with increasing M at given concentration was observed. In several instances, the self-diffusion measured data and fitted model suggests an approach to reptational scaling. The second example describes a study of reversible helix-to-coil transition in m-cresol of poly(ε-carbobenzyloxy-L-lysine), PCBL, both as a free macromolecule and when tethered to silica particles. 1H NMR showed the temperature range where the transition occurs. T1 NMR experiments revealed that free PCBL shows two split modes while the tethered PCBL had only one mode displaying three domains as a function of temperature. The observed differences between the two systems were associated with the presence of random coil end fragments during folding-unfolding of PCBL chain into a rod structure. Dedicated to the memory of our colleague and friend Dale Treleaven.

Investigation of polypeptide structure-property relationship by proton (H1)/spin-lattice relaxation time (T1) nuclear magnetic resonance and pulsed gradient spin echo (PGSE)

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.