Wong, Alan and Laurencin, Danielle and Wu, Gang and Dupree, Ray and Smith, Mark E. (2008) An ab initio quantum chemical investigation of Ca-43 NMR interaction parameters for the Ca2+ sites in organic complexes and in metalloproteins. Journal of Physical Chemistry A, 112 (40). pp. 9807-9813. ISSN 1520-5215Full text not available from this repository.
We have carried out an extensive ab initio quantum chemical (QC) Ca-43 NMR study on a series of Ca-O organic compounds and three different Ca-bound proteins and found that the HF/6-31G* level of function can reliably predict Ca-43 NMR interaction parameters (delta(iso) and chi(q)), especially for organic solids. This QC study finds correlations between Ca-O bond environment (mean distance and coordination number) and delta(iso)(Ca-43). Although relatively small values of chi(q)(Ca-43) are found for Ca-O organic compounds with a coordination number between 6 and 10, the QC shows that chi(q)(Ca-43) is sensitive to the Ca-O coordination geometry of the Ca2+ sites in metalloproteins-a potentially important observation. An application of such ab initio QC Ca-43 NMR studies is in characterizing the Ca-O bonding environment around target Ca2+ sites. As an example, we propose a new potential analytical approach using the absolute Ca-43 chemical shielding constant to investigate the hydration shell of Ca2+ in a dilute CaCl2 aqueous solution. Furthermore, by adopting a NMR methodology similar to that reported in Wong et al. Chem. Phys. Lett. 2006, 427, 201, natural abundance Ca-43 MAS NMR spectra of Ca(L-glutamate)(2)center dot 4H(2)O were recorded, and delta(iso)(Ca-43) and the quadrupolar parameter (P-q) were estimated to be 6.6 ppm and 0.8 MHz, respectively.
|Journal or Publication Title:||Journal of Physical Chemistry A|
|Deposited On:||29 Feb 2012 10:53|
|Last Modified:||03 Nov 2015 15:32|
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