Three quinolinone alkaloids, two acridone alkaloids and a flavones glycoside were isolated from the aerial parts of Glycosmis mauritiana. These compounds were characterized as 7, 8-Dimethoxy-2,2,6-trimethyl-pyrano qui...Three quinolinone alkaloids, two acridone alkaloids and a flavones glycoside were isolated from the aerial parts of Glycosmis mauritiana. These compounds were characterized as 7, 8-Dimethoxy-2,2,6-trimethyl-pyrano quinolin-5-one, 4-Methoxy 1-methyl quinolin-2-one, 6-Hydroxy N-methyl 2,3-furo-quinolin-4-one, 1-Hydroxy-10-methyl acridone, 1- Hydroxy-2, 3-dimethoxy-10-methylacridin-9-one and Luteolin-4'-O-[α-L-rhamnopyranosyl-(1→2)-{α-L-rhamnopyra- nosyl-(1→6)}-β-D-glycopyranoside]. The isolated compounds were characterized by UV, IR and N. M. R (1H, 13C) studies.展开更多
Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has bee...Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has been proved to be efficient tunneling mediator. While how it exactly modulates charge transport in a long peptide sequence remains poorly explored. In this work, we studied charge transport of a model peptide junction, where oligo-alanine peptide was doped by histidine at different position,and the series of peptides were self-assembled into a monolayer on gold electrode with soft EGa In as top electrode to form molecular junction. It was found that histidine increased the overall conductance of the peptide, meanwhile, its position modulated the conductance as well. Quantitative analysis by transport model and ultraviolet photoelectron spectroscopy(UPS) indicated a sequence dependent energy landscape of the tunneling barrier of the junction. Density-functional theory(DFT) calculation on the electronic structure of histidine doped oligo-alanine peptides revealed localized highest occupied molecular orbital(HOMO) on imidazole group of the histidine, which decreased charge transport barrier.展开更多
文摘Three quinolinone alkaloids, two acridone alkaloids and a flavones glycoside were isolated from the aerial parts of Glycosmis mauritiana. These compounds were characterized as 7, 8-Dimethoxy-2,2,6-trimethyl-pyrano quinolin-5-one, 4-Methoxy 1-methyl quinolin-2-one, 6-Hydroxy N-methyl 2,3-furo-quinolin-4-one, 1-Hydroxy-10-methyl acridone, 1- Hydroxy-2, 3-dimethoxy-10-methylacridin-9-one and Luteolin-4'-O-[α-L-rhamnopyranosyl-(1→2)-{α-L-rhamnopyra- nosyl-(1→6)}-β-D-glycopyranoside]. The isolated compounds were characterized by UV, IR and N. M. R (1H, 13C) studies.
基金supported by the National Natural Science Foundation of China (Nos. 21773169, 21973069, 21805144)Natural Science Foundation of Zhejiang Province (No. LY18B020016)the PEIYANG Young Scholars Program of Tianjin University (No. 2018XRX-0007)。
文摘Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has been proved to be efficient tunneling mediator. While how it exactly modulates charge transport in a long peptide sequence remains poorly explored. In this work, we studied charge transport of a model peptide junction, where oligo-alanine peptide was doped by histidine at different position,and the series of peptides were self-assembled into a monolayer on gold electrode with soft EGa In as top electrode to form molecular junction. It was found that histidine increased the overall conductance of the peptide, meanwhile, its position modulated the conductance as well. Quantitative analysis by transport model and ultraviolet photoelectron spectroscopy(UPS) indicated a sequence dependent energy landscape of the tunneling barrier of the junction. Density-functional theory(DFT) calculation on the electronic structure of histidine doped oligo-alanine peptides revealed localized highest occupied molecular orbital(HOMO) on imidazole group of the histidine, which decreased charge transport barrier.
