Disentangling Crystallographic Inequivalence and Crystallographic Forms of l-Arginine by One- and Two-Dimensional Solid-State NMR Spectroscopy

Abstract

Overlapping (13)C or (15)N solid-state NMR spectra from crystallographically different forms of L-arginine hydrochloride can be separated by exploiting differential proton T(1) relaxation in conjunction with cross-polarization. Dipolar (13)C-(13)C and (15)N-(15)N two-dimensional correlation experiments reveal resonances belonging to crystallographically and magnetically inequivalent molecules.

Deciphering the Conformational Choreography of Zinc Coordination Complexes with Standard and Novel Proton NMR Techniques Combined with DFT Methods

“…An interesting adapted spectroscopic tool used to disentangle different conformations and coordinationm odes in ag iven media is the proton spin-lattice relaxation time, T 1 . [25] As shown in Figure S5, measurements of T 1 1 Hr elaxation times (at T = 214 K) in the inversionr ecovery experiment imply the computing of series of 1D 1 Hs pectra with ap re-filter block (1808Àt). Evolution of signal intensity of each proton as af unction of t can be fitted according to Bloch equations in ordert oo btain T 1 1 Hv alues (FigureS5).…”

Restoring symmetry in two-dimensional solid-state NMR correlation spectra

“…PARISxy consists of a block of m pairs (m = 1 or 2) of phase-alternated pulses [(x)(Àx)] m , followed by a phase-shifted block [(y)(Ày)] m [3]. Each version creates different sets of recoupling bands which allows their complementary use and flexible exploitation over a very broad range of spinning frequencies and static magnetic fields [3][4][5][6]. In the present work, with moderate spinning frequencies 20 < m rot < 30 kHz and a medium static magnetic field of 9.4 T, PARISxy (m = 1) naturally appears to be the method of choice [3].…”

“…Magnetization transfer can be brought about either via through-bond scalar couplings or via through-space dipolar interactions, provided the latter are 'recoupled' to cancel their elimination by magic angle spinning (MAS). To promote dipolar recoupling, we developed PARIS [2] and PARISxy [3] methods which permit one to achieve an efficient exchange of magnetization over a wide range of spinning frequencies and static magnetic fields and to record sensitive 2D correlation spectra of microcrystalline proteins [4], amyloid fibrils [5] and mixtures of crystallographic forms [6].…”

Probing Structural and Motional Features of the C-Terminal Part of the Human Centrin 2/P17-XPC Microcrystalline Complex by Solid-State NMR Spectroscopy

“…PARIS is also largely immune to the inhomogeneity of the rf field, 19 so that the full sample volume effectively contributes to the signal whatever the spinning frequency. Very recently, we used the PARIS approach to record sensitive 2D correlation spectra of a microcrystalline protein, 32 amyloid fibrils, 33 and mixtures of crystallographic forms 34 and to restore the symmetry in 2D correlation experiments. 35 All experiments presented in this part were C correlation spectra of sample A (left) and sample B (right) recorded on a 400 MHz spectrometer by using PARIS recoupling with a proton rf amplitude ν 1H = 15 kHz during a mixing time of 50 ms.…”