Conformational dependence of the intrinsic acidity of the aspartic acid residue sidechain in N-acetyl-L-aspartic acid-N '-methylamide
The sidechain conformational potential energy hypersurfaces (PEHS) for the gamma(L), beta(L), alpha(L), and alpha(D) backbone conformations of N-acetyl-L-aspartate-M-methylamide were generated. Of the 81 possible conformers initially expected for the aspartate residue, only seven were found after ge...
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Main Authors: | |
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Format: | Article |
Published: |
2003
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Series: | JOURNAL OF MOLECULAR STRUCTURE: THEOCHEM
620 No. 2-3 |
Subjects: | |
doi: | 10.1016/S0166-1280(02)00639-5 |
mtmt: | 1132561 |
Online Access: | http://publicatio.bibl.u-szeged.hu/28638 |
Summary: | The sidechain conformational potential energy hypersurfaces (PEHS) for the gamma(L), beta(L), alpha(L), and alpha(D) backbone conformations of N-acetyl-L-aspartate-M-methylamide were generated. Of the 81 possible conformers initially expected for the aspartate residue, only seven were found after geometric optimizations at the B3LYP/6-31G(d) level of theory. No stable conformers could be located in the delta(L), epsilon(L), gamma(D), delta(D), and epsilon(D) backbone conformations. The 'adiabatic' deprotonation energies for the endo and exo forms of N-acetyl-L-aspartic acid-N'-methylamide were calculated by comparing their optimized relative energies against those found for the seven stable conformers of N-acetyl-L-aspartate-N'-methylamide. Sideehain conformational PEHSs were also generated for the estimation of 'vertical' deprotonation energies for both endo and exo forms of N-acetyl-L-aspartic acid-N'-methylamide. All backbone-sidechain (N-H...-O-C) and backbone-backbone (N-(HO)-O-...=C) hydrogen bond interactions were analyzed. A total of two backbone-backbone and four backbone-sidechain interactions were found for N-acetyl-L-aspartate-N'-methylamide. The deprotonated sidechain of N-acetyl-L-aspartate-N'-methylamide may allow the aspartyl residue to form strong hydrogen bond interactions (since it is negatively charged) which may be significant in such processes as protein-ligand recognition and ligand binding. As a primary example, the molecular geometry of the aspartyl residue may be important in peptide folding, such as that. in the RGD tripeptide. (C) 2002 Elsevier science B.V. All rights reserved. |
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Physical Description: | 231-255 |
ISSN: | 0166-1280 |