The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coup...The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coupling of triplet state of the minimal energy crossing point(CP)with their singlet states and of the zerofield splitting(ZFS)parameters of the triplet states,including the full one-and two-electron terms of the BreitPauli Hamiltonian.There are two key crossing points along this two-state reaction pathway.The first crossing point—CP2 exists near^1B.The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region.Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong,the reaction system will occur the reverse intersystem crossing from T_1 to S_0.Therefore,its spin-flip efficiency may be lower.The second crossing point,CP3will again change its spin multiplicity from the singlet state to the triplet state in the Co-Cr bond activation pathway,leading to a decrease in the barrier height of^1TS(CF)from19.5 to 9.5 kcal/mol(1cal=4.182 J),and the efficiency of intersystem crossing from S_0 to T_1 is high because the larger spin-orbit coupling(SOC)matrix elements will result in the overpopulations of the three sublevels of T_1(3.30×10^(-1),3.32×10^(-1),and 3.38×10^(-1),respectively).展开更多
The C2 domain originally referred to the second of four constant structural motifs in protein kinase C (PKC). Now this domain represents a large structural family sharing a homologous dimensional structure in many ...The C2 domain originally referred to the second of four constant structural motifs in protein kinase C (PKC). Now this domain represents a large structural family sharing a homologous dimensional structure in many proteins that play important roles in many organisms. The C2A domain is one of the two C2 domains of synaptotagmin I involved in the Ca 2+ regulation of exocytosis. This domain is mostly composed of β sheet except for a small fraction of α helix, and therefore provides an ideal model for a protein folding study. In this report, the unfolding equilibrium of the C2A domain in guanidine hydrochloride (GdnHCl) containing solutions has been studied using ultraviolet (UV) difference spectrum, fluorescence spectrum, size exclusion chromatography (SEC), and circular dichroism (CD) spectrum. The results suggest that unfolding of the C2A domain occurs as a two state process during GdnHCl titration. By examining the changes of both tertiary structure and secondary structure, no intermediates could be detected during this unfolding study. However, it has been found that the native state of the C2A domain has a large hydrophobic surface. This result suggests that as a fragment of a protein, the C2A domain itself may exist in a state with large hydrophobic surface. This hydrophobic surface may be the molecular basis for interaction between domains in the whole protein. Furthermore, the hydrophobic behavior may play a role during the oligomerization of synaptotagmin.展开更多
This paper has improved Hickman's nonadiabatic collision model by substituting Hickman's constant velocity classical straight line trajectory approximation with the solution of motion equation mR=-dV(R)/dR, an...This paper has improved Hickman's nonadiabatic collision model by substituting Hickman's constant velocity classical straight line trajectory approximation with the solution of motion equation mR=-dV(R)/dR, and has calculated the cross sections of ion-pair formation Cs+O2 -Cs++O2- with the improved nonadiabatic collision model (INCM). A comparison of our results with other theoretical and experimental results has been made.展开更多
基金supported by the National Natural Science Foundation of China(21263022)University Research Fund of Gansu Province Financial Department,and"QingLan"Talent Engineering Funds of Tianshui Normal University
文摘The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coupling of triplet state of the minimal energy crossing point(CP)with their singlet states and of the zerofield splitting(ZFS)parameters of the triplet states,including the full one-and two-electron terms of the BreitPauli Hamiltonian.There are two key crossing points along this two-state reaction pathway.The first crossing point—CP2 exists near^1B.The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region.Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong,the reaction system will occur the reverse intersystem crossing from T_1 to S_0.Therefore,its spin-flip efficiency may be lower.The second crossing point,CP3will again change its spin multiplicity from the singlet state to the triplet state in the Co-Cr bond activation pathway,leading to a decrease in the barrier height of^1TS(CF)from19.5 to 9.5 kcal/mol(1cal=4.182 J),and the efficiency of intersystem crossing from S_0 to T_1 is high because the larger spin-orbit coupling(SOC)matrix elements will result in the overpopulations of the three sublevels of T_1(3.30×10^(-1),3.32×10^(-1),and 3.38×10^(-1),respectively).
基金Project (51164007) supported by the National Natural Science Foundation of ChinaProject (2011M501288) supported by China Postdoctoral Science Foundation
基金Supported by the National Key Basic Research Specific Foundation of China(No.G19990 75 6 0 7)
文摘The C2 domain originally referred to the second of four constant structural motifs in protein kinase C (PKC). Now this domain represents a large structural family sharing a homologous dimensional structure in many proteins that play important roles in many organisms. The C2A domain is one of the two C2 domains of synaptotagmin I involved in the Ca 2+ regulation of exocytosis. This domain is mostly composed of β sheet except for a small fraction of α helix, and therefore provides an ideal model for a protein folding study. In this report, the unfolding equilibrium of the C2A domain in guanidine hydrochloride (GdnHCl) containing solutions has been studied using ultraviolet (UV) difference spectrum, fluorescence spectrum, size exclusion chromatography (SEC), and circular dichroism (CD) spectrum. The results suggest that unfolding of the C2A domain occurs as a two state process during GdnHCl titration. By examining the changes of both tertiary structure and secondary structure, no intermediates could be detected during this unfolding study. However, it has been found that the native state of the C2A domain has a large hydrophobic surface. This result suggests that as a fragment of a protein, the C2A domain itself may exist in a state with large hydrophobic surface. This hydrophobic surface may be the molecular basis for interaction between domains in the whole protein. Furthermore, the hydrophobic behavior may play a role during the oligomerization of synaptotagmin.
基金Project supported by the National Natural Science Foundation of China and the Special DoctoralFund of the Chinese Education Committee.
文摘This paper has improved Hickman's nonadiabatic collision model by substituting Hickman's constant velocity classical straight line trajectory approximation with the solution of motion equation mR=-dV(R)/dR, and has calculated the cross sections of ion-pair formation Cs+O2 -Cs++O2- with the improved nonadiabatic collision model (INCM). A comparison of our results with other theoretical and experimental results has been made.
