Chemistry Reference
In-Depth Information
[
182
]. However, data acquisition time is rather long even for samples with high
concentrations (ca. mM). Implementation of fast NMR methods such as non-
uniform sampling in the indirect dimension significantly reduced experimental
times [
183
]. Such a strategy will open new avenues to applications of
13
CNMR
to take advantage of the favorable heteronuclear chemical shift dispersion in
biological systems, especially for systems of increasing size.
Chemical shifts of selective nuclei (
113/111
Cd,
209
Pb, and
195
Pt) are sensitive
towards types of ligands (N, O, and S), numbers, and geometries, and will continue
to play a role in characterization of metal-protein local coordination. The ultra-field
NMR facilities direct observation of biologically important metal ions with half
integer, quadrupolar nuclei (e.g.,
67
Zn and
25
Mg) [
184
,
185
].
In spite of the availability of all these new techniques, their applications
to metalloproteins are currently sparse. There is an urgent need to promote these
advanced techniques in the scientific community through introducing integrated
software packages for experimental set-up, data processing, and analysis. This will
enable protein chemists and bioinorganic chemists, who are not NMR experts,
to employ the new techniques in their research. The combination of fast NMR
techniques,
13
C directly detected NMR with paramagnetic NMR, will offer great
possibilities in tackling new challenges in life science and will open new avenues for
NMR spectroscopy to be utilized not only in the characterization of single biomolecules,
e.g., structural and dynamical studies of proteins/metalloproteins and paramagnetic
proteins, short-lived macromolecules, and intrinsically unstructured proteins, but also
in the investigation of more complex systems to give an integrated view of interacting
molecular networks. In particular, ultra-fast NMR opens up new perspectives for NMR
structural investigations of unstable protein/metalloprotein samples and real-time site-
resolved studies of protein kinetics or monitoring folding/unfolding processes of
proteins/metalloproteins caused by ligand or metal binding/release.
Acknowledgements This work is supported by the Research Grants Council of Hong Kong
(HKU7043/06P, HKU2/06C, HKU7042/07P, HKU1/07C, HKU7038/08P, HKU7049/09P and
N-HKU752/09), Croucher Foundation.
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