Biomedical subjects

Akira Endou

Publications and source records attributed to Akira Endou.

4 recordsLinked to original sources

PubMed2006

Three-dimensional quantitative structure-activity relationship (3 D-QSAR) and docking studies on (benzothiazole-2-yl) acetonitrile derivatives as c-Jun N-terminal kinase-3 (JNK3) inhibitors.

Three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed for 44 (benzothiazole-2-yl) acetonitrile derivatives, inhibiting c-Jun N-terminal kinase-3 (JNK3). It includes molecular field analysis (MFA) and receptor surface analysis (RSA). The QSAR model was developed using 34 compounds and its predictive ability was assessed using a test set of 10 compounds. The predictive 3D-QSAR models have conventional r2 values of 0.849 and 0.766 for MFA and RSA, respectively; while the cross-validated coefficient r(cv)2 values of 0.616 and 0.605 for MFA and RSA, respectively. The results of the QSAR model were further compared with a structure-based analysis using docking studies with crystal structure of JNK3. Ligands bind in the ATP pocket and the hydrogen bond with GLN155 was found to be crucial for selectivity among other kinases. The results of 3D-QSAR and docking studies validate each other and hence, the combination of both methodologies provides a powerful tool directed to the design of novel and selective JNK3 inhibitors.

Acetonitriles↗

PubMed2006

First-principles study on proton dissociation properties of fluorocarbon- and hydrocarbon-based membranes in low humidity conditions.

We present a theoretical study on the proton dissociation properties of the membranes for polymer electrolyte fuel cells. A density functional theory method is used to study the influence of fluorocarbon and hydrocarbon backbones on proton dissociation, the interaction of water molecules with the sulfonic acid group, and the energy barriers for proton dissociation. Better proton dissociation properties of CH(3)SO(3)H compared to CF(3)SO(3)H are observed from statistical analyses of the optimized structures for both systems. However, the calculated energy barriers for proton dissociation are lower for CF(3)SO(3)H than for the CH(3)SO(3)H system. At the same time, the interaction of water molecules is stronger for CH(3)SO(3)H than for CF(3)SO(3)H. Also, the analysis of the hydrogen-bonding network in both systems shows that the number of hydrogen bonds formed around the sulfonic acid group in CH(3)SO(3)H is larger than that in CF(3)SO(3)H. Therefore, the decrease of the energy barrier with increasing number of coordinating water molecules, pronounced in the case of CH(3)SO(3)H, may lower the barrier, which enhances good proton conductivity of a hydrocarbon-based polymer in low humidity conditions. Thus the hydration ability of a sulfonic acid group is an important factor for realizing better proton dissociation in low humidity conditions.

Journal Article↗

PubMed2006

Tribochemical reaction dynamics of phosphoric ester lubricant additive by using a hybrid tight-binding quantum chemical molecular dynamics method.

To study the atomistic behavior of the phosphoric ester molecule on the nascent Fe surface under boundary lubrication conditions, we adopted a hybrid tight-binding quantum chemical molecular dynamics method. First, we investigated chemical interactions between phosphoric ester and the nascent Fe surface. Phosphoric ester was shown to interact with the nascent Fe surface, forming both covalent and ionic bonds. Formation and dissociation dynamics of covalent bonds during tribochemical reaction was clearly observed during the simulation. The effect of friction condition on the tribochemical reaction dynamics was then studied, and it was indicated that friction would influence the formation and the dissociation of covalent bonds. By using a hybrid tight-binding quantum chemical molecular dynamics method, we obtained insights on initial tribochemical reaction processes for the formation of tribofilm from the phosphoric ester molecule on the nascent Fe surface.

Journal Article↗

PubMed2003

Density functional study of the insertion and ring-opening mechanism of MCP over Cp2LaH and Cp2LuH catalysts.

The insertion and ring opening of methylenecyclopropane (MCP) catalyzed by Cp2LnH (Ln = La and Lu) was investigated using DFT method. Geometries and energies of the reactants, minima, and transition states for this reaction were obtained. The present study indicates the formation of Cp2LaH-MCP complex followed by 1,2-insertion through a tetrahedral transition state with subsequent ring opening at the proximal bond via hydrogen transfer transition state resulting in the formation of the final product.

Journal Article↗