Structure and Dynamics of Bulk Polymers by NMR-Methods

Pulsed field gradient NMR and nuclear magnetic relaxation studies of water mobility in hydrated collagen II

“…As mentioned in the experimental part, the data analysis immediately yields the distribution of the transverse relaxation times (without the necessity of any assumption on the number of monoexponentially relaxing components). This considerable extension of the data evaluation in comparison with single-component systems is inevitable, because polymer systems and hence also biological systems are generally characterized by a distribution of correlation times leading to a distribution of nuclear magnetic relaxation times (16). The meaning of this distribution is discussed in a forthcoming paper.…”

Hydration dependence of backbone and side chain polylysine dynamics: A 13C solid‐state NMR and IR spectroscopy study

“…Spectral densities J( ) are the Fourier-transformations of the correlation function of motion. Following the modelfree approach, 31 the correlation function of any anisotropic motion, in general case, can be written in a form of…”

“…The timescales and activation energies of these motions are typical for so-called ␥ (fast) and ␤ (slow) dynamic processes known from synthetic polymer studies. 31 The first process is a thermally activated local molecular motion of a relatively small kinetic unit of polymer within allowed spatial restrictions formed by bond lengths, valence angles, and van der Waals interactions with neighboring atoms. This process requires a variation of very few adjacent dihedral angles of a polymer chain.…”

Investigation of the molecular motion of spin-labeled lysozyme in solution by the use of ESP spectra and electron spin relaxation

“…Since no specific mechanism of anisotropic motion is known in the case under consideration, in order to obtain a picture of motion as much as possible independent of any particular model the approach introduced by Lipa¡ and Szabo [13] has been used. This so called "model-ffee" approach proved to be very helpful in investigation of dynamics in polymers and proteins by NMR [14,15]. Similar approach, named slowly relaxing local structure, has previously been introduced by Polnaszek and Freed [8b] in the ESR studies on liquid-crystalline solvents (see also [16] and references therein).…”

“…They should have characteristic times much longer than the individual local time of reorientations of a separate bond or of a small group of atoms for which the correlation times are usually in the range of 10-aa-10 -1~ s. It should be noted that the local concerted motion in lysozyme was revealed in our laboratory earlier by NMR ]30]. These motions had a wide correlation time distribution and were characterized by rather high amplitude (S 2 = 1 _ q2 ~ 0.6-0.7, q2 being anisotropy parameter derived from NMR data [14]) and the correlation time of about 0.2-0.3 ns. Maybe these motions were observed in our expe¡ with the viscosity variation.…”