The density functional theory based hybrid-method B3LYP was used to investigate the interaction of the halogen ions with crown tetraalanylpeptide which was the coronary structures of homodetic cyclotetraalapeptide and...The density functional theory based hybrid-method B3LYP was used to investigate the interaction of the halogen ions with crown tetraalanylpeptide which was the coronary structures of homodetic cyclotetraalapeptide and was represented as the model basic. Many properties including combination energy, optimum geometry structures and population analysis were calculated. It was shown that there was scarcely any change in the coronary structure of C4-Ala after combination with X. The electrons moved from halogen ions to C4-Ala during the combining process. Combination of C4-Ala with F was obviously stronger than that of Cl^- and Br. When the energy of C4-Ala-X was at minimum, the distances between halogen ions and the center of C4-Ala were 0.084 nm, 0.210 nm and 0.200 nm, respectively.展开更多
Under the method of density functional theory, the geometry structures, values of energy and population analysis of the combo of crown tetraalanylpeptide （C4-AIa） with ions （Xn） are calculated, based on the founda...Under the method of density functional theory, the geometry structures, values of energy and population analysis of the combo of crown tetraalanylpeptide （C4-AIa） with ions （Xn） are calculated, based on the foundation of former studies. It was found that the coronary structure changed little whether in C4-Ala or C4-Ala-Xn, and the electrons transferred between C4-Ala and Xn at the mean time. There were coordinate bonds between Xn＋ and the nitrogen from -NH-, hydrogen bonds between Xa and the hydrogen from -NH-, and they became weaker when the radii of ions turned larger. Besides, the values of the single point bonding energy fluctuated gradually as a shape of saddle, but cations and anions located in opposite directions of the center of coronary structure when reach minimum, respectively.展开更多
One of the major obstacles facing the field of structural biology in the post genomic era is the inherent difficulty of analyzing the structure of membrane proteins under native conditions. The method of choice for st...One of the major obstacles facing the field of structural biology in the post genomic era is the inherent difficulty of analyzing the structure of membrane proteins under native conditions. The method of choice for studying such proteins is FTIR spectroscopy. Following the outbreaking of the severe acute respiratory syndrome （SARS） virus, in 2003, extensive work has been directed at elucidating the structure of the E transmembrane proteins of the SARS coronavirus. In this study, the secondary structure of the transmembrane a-helical bundles was analysised using the biophysical method site specific infrared dichroism （SSID）. Sixteen amino acids were isotopically labeled with （~3C=180） at different positions of the primary structure of the synthesized E protein CoV. The secondary structure was studied using Attenuated Total Internal Reflection （ATR） FTIR spectroscopy. Based on our findings, the presence of two possible H-bonding interactions between the carbonyl oxygen of two residues 26 and 31 （Phe and Leu） respectively with water molecules which may be trapped within the helix structure were postulatesed. These interactions may cause a change in this structure.展开更多
Crown peptide is a kind of special conformation found on the homodetic cyclopeptide, regular array about the main chain containing imido groups, and the monolithic conformation presents coronary analogy to crown ether...Crown peptide is a kind of special conformation found on the homodetic cyclopeptide, regular array about the main chain containing imido groups, and the monolithic conformation presents coronary analogy to crown ether. There are high symmetrical ionophores belonging to Cn point group. The channels or apertures can form easily for recognizing certain ion or molecular, and also the function of intending dual-recognition and the ability for transporting as ionophores can be possessed. Under the method of density functional theory, the geometry structures, values energy and population analysis of the combo of crown tetraalanylpeptide （C4-Ala） with NO3- and SO4/2- are calculated, based on the foundation of former studies. Compared with the structure of C4-AIa without NO3- and SO4/2- it is found that the coronary shape changes little in the complex of C4-Ala-YOm/n-, and the electrons transfer between C4-AIa and YOm/n- at the mean time. There are hydrogen bond between oxygen of YOm/n- and the hydrogen from imine groups of C4-AIa, and they become weaker when the average charge density lessens.展开更多
文摘The density functional theory based hybrid-method B3LYP was used to investigate the interaction of the halogen ions with crown tetraalanylpeptide which was the coronary structures of homodetic cyclotetraalapeptide and was represented as the model basic. Many properties including combination energy, optimum geometry structures and population analysis were calculated. It was shown that there was scarcely any change in the coronary structure of C4-Ala after combination with X. The electrons moved from halogen ions to C4-Ala during the combining process. Combination of C4-Ala with F was obviously stronger than that of Cl^- and Br. When the energy of C4-Ala-X was at minimum, the distances between halogen ions and the center of C4-Ala were 0.084 nm, 0.210 nm and 0.200 nm, respectively.
文摘Under the method of density functional theory, the geometry structures, values of energy and population analysis of the combo of crown tetraalanylpeptide （C4-AIa） with ions （Xn） are calculated, based on the foundation of former studies. It was found that the coronary structure changed little whether in C4-Ala or C4-Ala-Xn, and the electrons transferred between C4-Ala and Xn at the mean time. There were coordinate bonds between Xn＋ and the nitrogen from -NH-, hydrogen bonds between Xa and the hydrogen from -NH-, and they became weaker when the radii of ions turned larger. Besides, the values of the single point bonding energy fluctuated gradually as a shape of saddle, but cations and anions located in opposite directions of the center of coronary structure when reach minimum, respectively.
文摘One of the major obstacles facing the field of structural biology in the post genomic era is the inherent difficulty of analyzing the structure of membrane proteins under native conditions. The method of choice for studying such proteins is FTIR spectroscopy. Following the outbreaking of the severe acute respiratory syndrome （SARS） virus, in 2003, extensive work has been directed at elucidating the structure of the E transmembrane proteins of the SARS coronavirus. In this study, the secondary structure of the transmembrane a-helical bundles was analysised using the biophysical method site specific infrared dichroism （SSID）. Sixteen amino acids were isotopically labeled with （~3C=180） at different positions of the primary structure of the synthesized E protein CoV. The secondary structure was studied using Attenuated Total Internal Reflection （ATR） FTIR spectroscopy. Based on our findings, the presence of two possible H-bonding interactions between the carbonyl oxygen of two residues 26 and 31 （Phe and Leu） respectively with water molecules which may be trapped within the helix structure were postulatesed. These interactions may cause a change in this structure.
文摘Crown peptide is a kind of special conformation found on the homodetic cyclopeptide, regular array about the main chain containing imido groups, and the monolithic conformation presents coronary analogy to crown ether. There are high symmetrical ionophores belonging to Cn point group. The channels or apertures can form easily for recognizing certain ion or molecular, and also the function of intending dual-recognition and the ability for transporting as ionophores can be possessed. Under the method of density functional theory, the geometry structures, values energy and population analysis of the combo of crown tetraalanylpeptide （C4-Ala） with NO3- and SO4/2- are calculated, based on the foundation of former studies. Compared with the structure of C4-AIa without NO3- and SO4/2- it is found that the coronary shape changes little in the complex of C4-Ala-YOm/n-, and the electrons transfer between C4-AIa and YOm/n- at the mean time. There are hydrogen bond between oxygen of YOm/n- and the hydrogen from imine groups of C4-AIa, and they become weaker when the average charge density lessens.
