The stability of three asphaltene-hydrogen donor systems,namely asphaltene-1-methylnaphthalene,asphaltene-tetralin,and asphaltene-decalin,with a mass ratio of 1:10 was investigated using the Turbiscan stability analyz...The stability of three asphaltene-hydrogen donor systems,namely asphaltene-1-methylnaphthalene,asphaltene-tetralin,and asphaltene-decalin,with a mass ratio of 1:10 was investigated using the Turbiscan stability analyzer.The interactions between hydrogen donor molecules and asphaltene units were simulated and calculated using Gaussian and Multiwfn,and then,noncovalent interaction analysis was performed.The results showed that the stability of the three asphaltene-hydrogen donor systems decreased as follows:asphaltene-1-methylnaphthalene>asphaltene-tetralin>asphaltene-decalin.The stability differences among the three systems were due to the different interactions between the hydrogen donor molecules and the asphaltene unit.The T-stacking interaction strength between the hydrogen donor molecules and the asphaltene units decreased as follows:1-methylnaphthalene-asphaltene unit>tetralin-asphaltene unit>decalin-asphaltene unit.Qualitative analysis indicates that the T-stacking interactions between the hydrogen donor molecules and the asphaltene units were mainly van der Waals forces,and the proportions of hydrogen bonds in the weak interaction differed among the systems.展开更多
Industrial growth in recent years led to air pollution and an increase in concentration of hazardous gases such as O<sub>3</sub> and NO. Developing new materials is important to detect and reduce air pollu...Industrial growth in recent years led to air pollution and an increase in concentration of hazardous gases such as O<sub>3</sub> and NO. Developing new materials is important to detect and reduce air pollutants. While catalytic decomposition and zeolites are traditional ways used to reduce the amount of these gases. We need to develop and explore new promising materials. Covalent organic framework (COF) has become an attractive platform for researcher due to its extended robust covalent bonds, porosity, and crystallinity. In this study, first principal calculations were performed for gases adsorption using COFs containing nitrogen and π-bonds. Different building blocks (BBs) and linkers (LINKs/LINK1 & LINK2) were investigated by means of density functional theory (DFT) calculations with B3LYP and 3-21G basis sets to calculate the binding energies of gases @COF systems. Electrostatic potential maps (ESPM), Mulliken charges and non-covalent interaction (NCI) are used to understand the type of interactions between gas and COFs fragments. O3 was found to bind strongly with COF system in comparison with NO which could make COF a useful selective material for mixed gases environment for sensing and removal application.展开更多
Cytochrome P450（CYP） 2El is a dual function monoxygenase with a crucial role in the metabolism of 6% of drugs on the market at present. The enzyme is of tremendous interest for its association with alcohol consumpti...Cytochrome P450（CYP） 2El is a dual function monoxygenase with a crucial role in the metabolism of 6% of drugs on the market at present. The enzyme is of tremendous interest for its association with alcohol consumption, diabetes, obesity and fasting. Despite the abundant experimental mutagenesis data, the molecular origin and the structural motifs for the enzymatic activity deficiencies have not been rationalized at the atomic level. In this regard, we have investigated the effects of mutation on the structural and energetic characteristics upon single point mutations in CYP2E1, N219D and $366C. The molecular dynamics（MD） simulation combined with quantum mechanics/molecular mechanics（QM/MM） and noncovalent interaction（NCI） analysis was carried out on CYP2EI and its two mutants. The results highlight the critical role of Phe207, which is responsible for both structural flexibility and energetic variation, shortening the gap between the theory and the experimentally observed results of enzymatic activity decrease, The underlying molecular mechanism of the enzymatic activity deficiencies for mutants may be attributed to the changes of spatial position of Phe207 in the two mutants. This work provides particular explanations to how mutations affect ligand-receptor interactions based on combined MD and QM/MM calculations. Furthermore, the mutational effects on the activity of CYP2E1 obtained in the present study are beneficial to both the experimental and the computational works of CYPs and may allow researchers to achieve desirable changes in enzymatic activity.展开更多
文摘The stability of three asphaltene-hydrogen donor systems,namely asphaltene-1-methylnaphthalene,asphaltene-tetralin,and asphaltene-decalin,with a mass ratio of 1:10 was investigated using the Turbiscan stability analyzer.The interactions between hydrogen donor molecules and asphaltene units were simulated and calculated using Gaussian and Multiwfn,and then,noncovalent interaction analysis was performed.The results showed that the stability of the three asphaltene-hydrogen donor systems decreased as follows:asphaltene-1-methylnaphthalene>asphaltene-tetralin>asphaltene-decalin.The stability differences among the three systems were due to the different interactions between the hydrogen donor molecules and the asphaltene unit.The T-stacking interaction strength between the hydrogen donor molecules and the asphaltene units decreased as follows:1-methylnaphthalene-asphaltene unit>tetralin-asphaltene unit>decalin-asphaltene unit.Qualitative analysis indicates that the T-stacking interactions between the hydrogen donor molecules and the asphaltene units were mainly van der Waals forces,and the proportions of hydrogen bonds in the weak interaction differed among the systems.
文摘Industrial growth in recent years led to air pollution and an increase in concentration of hazardous gases such as O<sub>3</sub> and NO. Developing new materials is important to detect and reduce air pollutants. While catalytic decomposition and zeolites are traditional ways used to reduce the amount of these gases. We need to develop and explore new promising materials. Covalent organic framework (COF) has become an attractive platform for researcher due to its extended robust covalent bonds, porosity, and crystallinity. In this study, first principal calculations were performed for gases adsorption using COFs containing nitrogen and π-bonds. Different building blocks (BBs) and linkers (LINKs/LINK1 & LINK2) were investigated by means of density functional theory (DFT) calculations with B3LYP and 3-21G basis sets to calculate the binding energies of gases @COF systems. Electrostatic potential maps (ESPM), Mulliken charges and non-covalent interaction (NCI) are used to understand the type of interactions between gas and COFs fragments. O3 was found to bind strongly with COF system in comparison with NO which could make COF a useful selective material for mixed gases environment for sensing and removal application.
基金Supported by the National Natural Science Foundation of China（No.21273095）.
文摘Cytochrome P450（CYP） 2El is a dual function monoxygenase with a crucial role in the metabolism of 6% of drugs on the market at present. The enzyme is of tremendous interest for its association with alcohol consumption, diabetes, obesity and fasting. Despite the abundant experimental mutagenesis data, the molecular origin and the structural motifs for the enzymatic activity deficiencies have not been rationalized at the atomic level. In this regard, we have investigated the effects of mutation on the structural and energetic characteristics upon single point mutations in CYP2E1, N219D and $366C. The molecular dynamics（MD） simulation combined with quantum mechanics/molecular mechanics（QM/MM） and noncovalent interaction（NCI） analysis was carried out on CYP2EI and its two mutants. The results highlight the critical role of Phe207, which is responsible for both structural flexibility and energetic variation, shortening the gap between the theory and the experimentally observed results of enzymatic activity decrease, The underlying molecular mechanism of the enzymatic activity deficiencies for mutants may be attributed to the changes of spatial position of Phe207 in the two mutants. This work provides particular explanations to how mutations affect ligand-receptor interactions based on combined MD and QM/MM calculations. Furthermore, the mutational effects on the activity of CYP2E1 obtained in the present study are beneficial to both the experimental and the computational works of CYPs and may allow researchers to achieve desirable changes in enzymatic activity.
