New Carbon-Detected Protein NMR Experiments Using CryoProbes

NMR Spectroscopy of Paramagnetic Metalloproteins

“…In some lucky cases, metal-nucleus-proton scalar connectivities can be exploited to prove the existence of a metal-protein bond. This is the case with 113 Cd [3][4][5][6] and 199 Hg, [7,8] for which metal-ligand couplings can be detected by heteronuclear 2D experiments such as metal-proton correlation or metal-edited spectra. These experiments provide crosspeaks originating from the metal-nucleus-proton couplings, which are directly related to the MXCH dihedral angle (M = metal ion; X = donor atom; Figure 1).…”

“…Finally, a section is dedicated to the significant progress made on 13 C direct detection, which reduces the negative effects of paramagnetism and may constitute a new chapter in the whole field of NMR spectroscopy. 113 CdÀSÀCÀH dihedral angle, q, and the metal-proton coupling constant, 3 J, in Cd 7 -metallothionein and Cd-rubredoxin, with the best-fit curve shown. [9] ChemBioChem larger than a proton) and have relaxation times varying from 10 À13 -10 À8 s depending on the atomic number of the metal and on the particular occupancy of the atomic orbitals.…”

“…However, the gain in resolution due to the reduced broadening of the NMR lines is such as to compensate, at least partially, for the loss in sensitivity. [113] Furthermore, improvements in hardware aim at increasing sensitivity in 13 C detection. Indeed, several applications of 13 C direct detection to paramagnetic macromolecules have recently appeared in the literature.…”

Exclusively Heteronuclear NMR Experiments to Obtain Structural and Dynamic Information on Proteins

“…[27][28][29][30][31] If transverse relaxation is not prohibitively fast, 1 H polarization ( 1 H start) can be used to increase the sensitivity of exclusively heteronuclear multidimensional experiments, while still exploiting only heteronuclear chemical shifts in all dimensions. [32,33] Proton chemical-shift evolution can of course be implemented in the indirect dimension of 13 C direct-detection NMR experiments, as proposed for the study of proteins [34][35][36][37] and nucleic acids. [38,39] Finally, the development of strategies to overcome problems related to 13 C detection in solution, such as homonuclear decoupling, [10,22,40] which have initially been stimulated by experiments developed for solid-state applications, [41,42] as well as common and complementary aspects of 13 C detection in solution and in the solid state, [13,17,[43][44][45] are now creating a basis for cross-fertilization between these two areas of biomolecular NMR [46] that can be eventually combined to tackle challenging systems.…”

Two new asterosaponins from the starfish Asterias rubens: application of a cryogenic NMR probe head

“…To provide both the complete 1 H and 13 C signal assignments, the identified target compounds are then preparatively isolated either by semi-preparative LC or by repeated chromatography on an analytical column and are subsequently submitted to one-and two-dimensional off-line NMR techniques. However, as the compounds of interest are in most cases minor compounds, the amount of unknown compounds obtained by this approach may be small, particularly if the final isolation is performed on an analytical scale.…”