排序方式: 共有35条查询结果,搜索用时 21 毫秒
1.
Lakshmipathi Senthilkumar Palanivel Umadevi Kumaranathapuram Natarajan Sweety Nithya Ponmalai Kolandaivel 《Journal of molecular modeling》2013,19(8):3411-3425
Twenty cocaine–water complexes were studied using density functional theory (DFT) B3LYP/6-311++G** level to understand their geometries, energies, vibrational frequencies, charge transfer and topological parameters. Among the 20 complexes, 12 are neutral and eight are protonated in the cocaine-water complexes. Based on the interaction energy, the protonated complexes are more stable than the neutral complexes. In both complexes, the most stable structure involves the hydrogen bond with water at nitrogen atom in the tropane ring and C?=?O groups in methyl ester. Carbonyl groups in benzoyl and methyl ester is the most reactive site in both forms and it is responsible for the stability order. The calculated topological results show that the interactions involved in the hydrogen bond are electrostatic dominant. Natural bond orbital (NBO) analysis confirms the presence of hydrogen bond and it supports the stability order. Atoms in molecules (AIM) and NBO analysis confirms the C-H?·?·?·?O hydrogen bonds formed between the cocaine-water complexes are blue shifted in nature. 相似文献
2.
Balagopal P Pandey M Chandramohan K Somanathan T Kumar A 《World journal of surgical oncology》2003,1(1):4
Background
Choriocarcinoma is an aggressive neoplasm arising in the body of the uterus. The disease normally spreads to lung and brain. 相似文献3.
The switching propensity and maximum probability of occurrence of the side chain imidazole group in the dipeptide cyclo(His–Pro)
(CHP) were studied by applying molecular dynamics simulations and density functional theory. The atomistic behaviour of CHP
with the neurotoxins glutamate (E) and paraquat (Pq) were also explored; E and Pq engage in hydrogen bond formation with the
diketopiperazine (DKP) ring of the dipeptide, with which E shows a profound interaction, as confirmed further by NH and CO
stretching vibrational frequencies. The effect of CHP was found to be greater on E than on Pq neurotoxin. A ring puckering
study indicated a twist boat conformation for the six-membered DKP ring. Molecular electrostatic potential (MESP) mapping
was also used to explore the hydrogen bond interactions prevailing between the neurotoxins and the DKP ring. The results of
this study reveal that the DKP ring of the dipeptide CHP can be expected to play a significant role in reducing effects such
as oxidative stress and cell death caused by neurotoxins. 相似文献
4.
Introduction
Development of cell therapies for repairing the intervertebral disc is limited by the lack of a source of healthy human disc cells. Stem cells, particularly mesenchymal stem cells, are seen as a potential source but differentiation strategies are limited by the lack of specific markers that can distinguish disc cells from articular chondrocytes. 相似文献5.
The quantum chemical and molecular dynamics studies have been performed to infer the structural changes of all-trans and all-cis
forms of cyclo[(1R,3S)-3-aminocyclohexanecarboxylicacid(γ-Acc)-α-Glycine(Gly)]3 hexapeptide. The backbone conformations of the above peptide have been analyzed using the valence and peptide deformation
angles applying B3LYP/6–311G** level of theory. The conformational preference of the backbone of all-trans and all-cis cyclo[(1R,3S)-γ-Acc-Gly]3 hexapeptides is found to depend on the puckering of cyclohexane rings. The non-uniform distribution of water inside the cavity
is observed, where sometimes water molecules formed a chain like conformation through hydrogen bond networks while traversing
the pore of all-cis cyclo[(1R,3S)-γ-Acc-Gly]3 peptide. Larger relaxation times of the order of a hundred to two hundred pico seconds for active site…water hydrogen bond
interactions were noticed. The hydrophobic nature of the cavity of all-trans cyclo[(1R,3S)-γ-Acc-Gly]3 due to the presence of cyclohexane moiety has been analyzed. Further this investigation emphasized on the non-transport of
molecules through the pore of all-trans cyclo[(1R,3S)-γ-Acc-Gly]3 peptide due to the obstruction produced by cyclohexane groups. 相似文献
6.
D Taruscio C Morciano P Laricchiuta P Mincarone F Palazzo CG Leo S Sabina R Guarino J Auld T Sejersen D Gavhed K Ritchie M Hilton-Boon J Manson PG Kanavos D Tordrup V Tzouma Y Le Cam J Senecat G Filippini S Minozzi C Del Giovane H Schünemann JJ Meerpohl B Prediger L Schell R Stefanov G Iskrov T Miteva-Katrandzhieva P Serrano-Aguilar L Perestelo-Perez MM Trujillo-Martín J Pérez-Ramos A Rivero-Santana A Brand H van Kranen K Bushby A Atalaia J Ramet L Siderius M Posada I Abaitua-Borda V Alonso Ferreira M Hens-Pérez FJ Manzanares 《Orphanet journal of rare diseases》2014,9(Z1):O14
7.
Ana C. Coan Brunno M. Campos Clarissa L. Yasuda Bruno Y. Kubota Felipe PG. Bergo Carlos AM. Guerreiro Fernando Cendes 《PloS one》2014,9(1)
Objective
Patients with temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) have diffuse subtle gray matter (GM) atrophy detectable by MRI quantification analyses. However, it is not clear whether the etiology and seizure frequency are associated with this atrophy. We aimed to evaluate the occurrence of GM atrophy and the influence of seizure frequency in patients with TLE and either normal MRI (TLE-NL) or MRI signs of HS (TLE-HS).Methods
We evaluated a group of 172 consecutive patients with unilateral TLE-HS or TLE-NL as defined by hippocampal volumetry and signal quantification (122 TLE-HS and 50 TLE-NL) plus a group of 82 healthy individuals. Voxel-based morphometry was performed with VBM8/SPM8 in 3T MRIs. Patients with up to three complex partial seizures and no generalized tonic-clonic seizures in the previous year were considered to have infrequent seizures. Those who did not fulfill these criteria were considered to have frequent seizures.Results
Patients with TLE-HS had more pronounced GM atrophy, including the ipsilateral mesial temporal structures, temporal lobe, bilateral thalami and pre/post-central gyri. Patients with TLE-NL had more subtle GM atrophy, including the ipsilateral orbitofrontal cortex, bilateral thalami and pre/post-central gyri. Both TLE-HS and TLE-NL showed increased GM volume in the contralateral pons. TLE-HS patients with frequent seizures had more pronounced GM atrophy in extra-temporal regions than TLE-HS with infrequent seizures. Patients with TLE-NL and infrequent seizures had no detectable GM atrophy. In both TLE-HS and TLE-NL, the duration of epilepsy correlated with GM atrophy in extra-hippocampal regions.Conclusion
Although a diffuse network GM atrophy occurs in both TLE-HS and TLE-NL, this is strikingly more evident in TLE-HS and in patients with frequent seizures. These findings suggest that neocortical atrophy in TLE is related to the ongoing seizures and epilepsy duration, while thalamic atrophy is more probably related to the original epileptogenic process. 相似文献8.
9.
R. Radhika S. Vijayakumar P. Kolandaivel 《Journal of biomolecular structure & dynamics》2018,36(6):1369-1401
The theoretical studies on DNA with the anticancer drug 6-Mercaptopurine (6-MP) are investigated using theoretical methods to shed light on drug designing. Among the DNA base pairs considered, 6-MP is stacked with GC with the highest interaction energy of –46.19 kcal/mol. Structural parameters revealed that structure of the DNA base pairs is deviated from the planarity of the equilibrium position due to the formation of hydrogen bonds and stacking interactions with 6-MP. These deviations are verified through the systematic comparison between X–H bond contraction and elongation and the associated blue shift and red shift values by both NBO analysis and vibrational analysis. Bent’s rule is verified for the C–H bond contraction in the 6-MP interacted base pairs. The AIM results disclose that the higher values of electron density (ρ) and Laplacian of electron density (?2ρ) indicate the increased overlap between the orbitals that represent the strong interaction and positive values of the total electron density show the closed-shell interaction. The relative sensitivity of the chemical shift values for the DNA base pairs with 6-MP is investigated to confirm the hydrogen bond strength. Molecular dynamics simulation studies of G-quadruplex DNA d(TGGGGT)4 with 6-MP revealed that the incorporation of 6-MP appears to cause local distortions and destabilize the G-quadruplex DNA. 相似文献
10.
A theoretical investigation on the interaction of myristic fatty acid (M) with Acutohaemolysin and Piratoxin-II of PLA2 family
is performed using two layered ONIOM (B3LYP/6-31G*: UFF) method. The results predict that though proteins show revulsion to
incoming fatty acid, the interaction of the phenyl ring of Phenylalanine restricts the passage of M through the channel. To
unveil the nature of interaction of M, quantum chemical studies are carried out on the palindromic tripeptides Alanine-Phenylalanine-Alanine
(AFA) and Alanine-Valine-Alanine (AVA) present in Acutohaemolysin and Piratoxin-II at B3LYP/6-311G** level of theory. The
mode of interaction of the fatty acid with protein is electrostatic, confirmed further through molecular electrostatic potential
(MEP) maps. The AFA shows stronger interaction than AVA, validating the impact of mutation on catalytic activity. Further
such strong interaction and hence the higher probability of prohibition for catalytic activity exists only when the fatty
acid interacts at the center of phenyl ring than at its edges. The preferred secondary structural configuration and conformational
properties of AVA and AFA also validate the strong interaction of fatty acid with Phenylalanine. In general, this theoretical
investigation shows that the loss of catalytic activity would take place only when fatty acid interacts at the center of phenyl
ring. 相似文献