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13 C shielding tensors of crystalline amino acids and peptides: Theoretical predictions based on periodic structure models
Author(s) -
Zheng Anmin,
Liu ShangBin,
Deng Feng
Publication year - 2008
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21118
Subject(s) - electromagnetic shielding , amino acid , computational chemistry , chemistry , physics , statistical physics , crystallography , molecular physics , chemical physics , materials science , quantum mechanics , biochemistry
Precise theoretical predictions of NMR parameters are helpful for the spectroscopic identification of complicated biological molecules, especially for the carbon shielding tensors in amino acids. The 13 C shielding tensors of various crystalline amino acids and peptides have been calculated using the gauge‐including projector augmented wave (GIPAW) method based on two different periodic structure models, namely that deduced from available crystallographic data and that from theoretically optimized structures. The incorporation of surrounding lattice effects is found to be crucial in obtaining reliable predictions of 13 C shielding tensors that are comparable to the experimental data. This is accomplished by refining the experimental crystallographic data of the amino acids and peptides at the GGA/PBE level by which more accurate intramolecular CH bond lengths and intermolecular hydrogen‐bonding interactions are obtained. Accordingly, more accurate predictions of 13 C shielding tensors comparable to the experimental results (within a maximum deviation of ±10 ppm) were achieved, rendering more explicit 13 C shielding tensors assignments for solid biological systems particularly for amino acids with multiple carboxyl carbons, such as asparagine, glutamine, and glutamic acid. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009