Density functional theory study of N–H…O=C hydrogen-bonding effects in structure of beta amyloid (Aþ): 17O and 14 N nuclear quadrupole resonance parameters

Karami, Leila and D.Esrafili, Mehdi and L. Hadipour, Nasser Density functional theory study of N–H…O=C hydrogen-bonding effects in structure of beta amyloid (Aþ): 17O and 14 N nuclear quadrupole resonance parameters. In: 11th Iranian Physical Chemistry Seminar-July 2008, July 2008, Ardabil, Iran.

[img] Text
23.pdf

Download (157kB)
Official URL: http://uma.ac.ir/

Abstract

The þ-amyloid proteins (Aþ), especially the variant Aþ1-42, are the primary constituent of the amyloid plaques which are characteristic of Alzheimer’s disease. Amyloid fibrils [1] are composed of cross-þ-sheets (i.e. the constituent þ-strands run perpendicular to the fiber axis). Hydrogen bonds (HBs) play a fundamental role in amyloid fibrils formation. Because hydrogen-bonding interactions are mainly electrostatic in nature, the techniques that deal with the charge distribution around the nuclei seem to be reliable techniques to characterize the nature of hydrogen bonds. Nuclear quadrupole resonance, NQR, spectroscopy is well-established as a versatile technique to study the details of the electronic and nuclear charge distribution around the nucleus of interest [2-3]. The quantum mechanical approaches have shown to be a very effective method in determination of charge distribution. It permits to estimate the electric field gradient (EFG) resulting from the whole molecular charges around nucleus. As for the high sensitivity to the electrostatic environment of nuclei, electronic structures and intermolecular interactions, such as hydrogen bonding (HB), can produce a significant influence on the EFG tensors. EFG is a traceless, symmetric second-rank tensor whose principal axes system (PAS) are chosen so that its components satisfy |qzz|≤|qyy|≤|qxx| (qij = 6 2V/6i6j) where i, j = x, y, and z, and V is the external electrostatic potential. The nuclear quadrupole coupling constant (NQCC) and asymmetry parameter (4Q) are those quantities determined experimentally by NQR. NQCC means the interaction energy between electric quadrupole moment, eQ, of nucleus and the EFG tensors arisen at the site of quadrupolar nucleus (Those nuclei with spin angular momentum greater than one-half (I>1/2) are quadrupole). 4Q parameter measures the EFG tensors deviation from cylindrical symmetry at the site of quadrupolar nucleus.

Item Type: Conference or Workshop Item (Paper)
Persian Title: Density functional theory study of N–H…O=C hydrogen-bonding effects in structure of beta amyloid (Aþ): 17O and 14 N nuclear quadrupole resonance parameters
Persian Abstract: -
Subjects: Divisions > Conferences > 11th Iranian Physical Chemistry Seminar- July 2008
Conferences > 11th Iranian Physical Chemistry Seminar- July 2008
Divisions: Conferences > 11th Iranian Physical Chemistry Seminar- July 2008
Subjects > Conferences > 11th Iranian Physical Chemistry Seminar- July 2008
Date Deposited: 17 Jun 2019 04:07
Last Modified: 17 Jun 2019 04:07
URI: http://repository.uma.ac.ir/id/eprint/6768

Actions (login required)

View Item View Item