title: Low concentration of a Gd-chelate increases the signal-to-noise ratio in fast pulsing BEST experiments.
abstract: Despite numerous developments in the past few years that aim to increase the sensitivity of NMR multidimensional experiments, NMR spectroscopy still suffers from intrinsic low sensitivity. In this report, we show that the combination of two developments in the field, the Band-selective Excitation Short-Transient (BEST) experiment [Schanda et al., J. Am. Chem. Soc., 128 (2006) 9042] and the addition of the nonionic paramagnetic gadolinium chelate gadodiamide into NMR samples, enhances the signal-to-noise ratio. This effect is shown here for four different proteins, three globular and one unfolded, of molecular weights ranging from 6.5 kDa to 40 kDa, using 2D BEST HSQC and 3D BEST triple resonance sequences. Moreover, we show that the increase in signal-to-noise ratio provided by the gadodiamide is higher for peak resonances with lower than average intensity in BEST experiments. It is interesting to note that these residues are on average the weakest ones in those experiments. In this case, the gadodiamide-mediated increase can reach a value of 60% for low and 30% for high molecular weight proteins respectively. An investigation into the origin of this "paramagnetic gain" in BEST experiments is presented.
authors.affiliation: CNRS UMR 5048, Centre de Biochimie Structurale, Montpellier, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Sibille
authors.forename: Gaëtan
authors.initials: G
authors.lastname: Bellot
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Hélène
authors.initials: H
authors.lastname: Déméné
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D045424:Complex Mixtures / Q000032:analysis* / Q000737:chemistry; D019786:Gadolinium DTPA / Q000032:analysis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011506:Proteins / Q000032:analysis* / Q000737:chemistry; D059629:Signal-To-Noise Ratio
chemical_list: D002614:Chelating Agents; D045424:Complex Mixtures; D011506:Proteins; C064925:gadodiamide; D019786:Gadolinium DTPA