An extended LCAC\|SW(Linear Combination of Arrangement Channels\|Scattering Wavefunction) quantum scattering dynamic method combined with \%ab initio\% quantum chemical calculations has been used to study the formatio...An extended LCAC\|SW(Linear Combination of Arrangement Channels\|Scattering Wavefunction) quantum scattering dynamic method combined with \%ab initio\% quantum chemical calculations has been used to study the formation mechanism of the resonance states for ion\|pair formation reaction Na+I\-2 Na\+++I\+-\-2. Resonance energy and width or lifetime for the first resonance peak were calculated. Resonance can be identified to Feshbach resonance and the physical interpretation was given.展开更多
The mechanisms about the water’s and methanol’s effects on the alcoholysis of N-benzyl-3-oxo-β-sultam together with their differences have been studied by using density func- tional theory at the B3LYP/6-31G＊ leve...The mechanisms about the water’s and methanol’s effects on the alcoholysis of N-benzyl-3-oxo-β-sultam together with their differences have been studied by using density func- tional theory at the B3LYP/6-31G＊ level. The results, in comparison with a previous study on the relative reaction without the assistance of water and methanol, show that the added water or methanol can remarkably reduce the energy barrier of alcoholysis reaction of N-benzyl-3-oxo- β-sultam and the most favorite pathway is the breaking of C–N bond instead of S–N. It is also found that the reaction energy barrier of methanol-assisted alcoholysis is a little higher than that of the water-assisted one.展开更多
Arylamine N-acetyltransferases （NATs, EC 2.3.1.5） catalyze the N-acetylation of primary arylamines, and play a key role in the biotransformation and metabolism of drugs, carcinogens, etc. In this paper, three possib...Arylamine N-acetyltransferases （NATs, EC 2.3.1.5） catalyze the N-acetylation of primary arylamines, and play a key role in the biotransformation and metabolism of drugs, carcinogens, etc. In this paper, three possible reaction mechanisms are investigated and the results indicate that if the acetyl group directly transfers from the donor to the acceptor, the high activation energies will make it hard to obtain the target products. When using histidine to mediate the acetylation process, these energies will drop in the 15-45 kJ/mol range. If the histidine residue is protonated, the corresponding energies will be decreased by about 35-87 kJ/mol. The calculations predict an enzymatic acetylation mechanism that undergoes a thiolate-imidazolium pair, which agrees with the experimental results very well.展开更多
文摘An extended LCAC\|SW(Linear Combination of Arrangement Channels\|Scattering Wavefunction) quantum scattering dynamic method combined with \%ab initio\% quantum chemical calculations has been used to study the formation mechanism of the resonance states for ion\|pair formation reaction Na+I\-2 Na\+++I\+-\-2. Resonance energy and width or lifetime for the first resonance peak were calculated. Resonance can be identified to Feshbach resonance and the physical interpretation was given.
基金This work was supported by the National Natural Science Foundation of China (No. 20373034 and 20603030)Post-doctor Research Foundation of Shandong Province (No. 200601007)
文摘The mechanisms about the water’s and methanol’s effects on the alcoholysis of N-benzyl-3-oxo-β-sultam together with their differences have been studied by using density func- tional theory at the B3LYP/6-31G＊ level. The results, in comparison with a previous study on the relative reaction without the assistance of water and methanol, show that the added water or methanol can remarkably reduce the energy barrier of alcoholysis reaction of N-benzyl-3-oxo- β-sultam and the most favorite pathway is the breaking of C–N bond instead of S–N. It is also found that the reaction energy barrier of methanol-assisted alcoholysis is a little higher than that of the water-assisted one.
基金the National Natural Scientific Foundation of China(No.20603030)the Youth Natural Science Foundation of Ludong University(No.042902)+1 种基金the Post-doctor Research Foundation of Shandong Province(No.200601007)the Youth Natural Science Foundation of Shandong Provincial Education Department(No.200139)
文摘Arylamine N-acetyltransferases （NATs, EC 2.3.1.5） catalyze the N-acetylation of primary arylamines, and play a key role in the biotransformation and metabolism of drugs, carcinogens, etc. In this paper, three possible reaction mechanisms are investigated and the results indicate that if the acetyl group directly transfers from the donor to the acceptor, the high activation energies will make it hard to obtain the target products. When using histidine to mediate the acetylation process, these energies will drop in the 15-45 kJ/mol range. If the histidine residue is protonated, the corresponding energies will be decreased by about 35-87 kJ/mol. The calculations predict an enzymatic acetylation mechanism that undergoes a thiolate-imidazolium pair, which agrees with the experimental results very well.
