Spectroscopic characteristics of the β-fructosyltransferase(EC2.4.1.9 FTS) from Aspergillus oryzae GX0011 was studied by ultraviolet absorbance spectrum,fluorescence spectrum and circular dichroism.The enzyme exhibit...Spectroscopic characteristics of the β-fructosyltransferase(EC2.4.1.9 FTS) from Aspergillus oryzae GX0011 was studied by ultraviolet absorbance spectrum,fluorescence spectrum and circular dichroism.The enzyme exhibited that the characteristic peaks of ultraviolet absorbance spectrum,of fluorescence emission spectrum were at 280nm and 343nm.In low concentration of ,the fluorescence quenching was in line with the Sterm-Volmer’s equation and the percentage of Trp residue reacted by was 0.72.By comparing the fluorescence spectra of FTS substrate-perturbation,it was implied that some inner Trp residues participated in catalysis and might be involved in the active site of the enzyme.Furthermore,the secondary structures of FTS were quantitatively determined by circular dichroism.The relative percentage content of each secondary structure were:25.1±0.8% α-helix,5.3±2.3% β-sheet,31.4±1.5%β-turn and 38.2±1.1% random coil respectively.展开更多
Molecular frame photoemission is a very sensitive probe of the photoionization （PI） dynamics of molecules. This paper reports a comparative study of non-resonant and resonant photoionization of D2 induced by VUV cir...Molecular frame photoemission is a very sensitive probe of the photoionization （PI） dynamics of molecules. This paper reports a comparative study of non-resonant and resonant photoionization of D2 induced by VUV circularly polarized synchrotron radiation at SOLEIL at the level of the molecular frame photoelectron angular distributions （MFPADs）. We use the vector correlation method which combines imaging and time-of-flight resolved electron-ion coincidence techniques, and a generalized formalism for the expression of the Ⅰ（χ, θe, Фe） MFPADs, where χ is the orientation of the molecular axis with respect to the light quantization axis and （θe, Фe） the electron emission direction in the molecular frame. Selected MFPADs for a molecule aligned parallel or perpendicular to linearly polarized light, or perpendicular to the propagation axis of circularly polarized light, are presented for dissociative photoionization （DPI） of D2 at two photon excitation energies, hv=19 eV, where direct PI is the only channel opened, and hv=32.5 eV, i.e. in the region involving resonant excitation of Q1 and Q2 doubly excited state series. We discuss in particular the properties of the circular dichroism characterizing photoemission in the molecular frame for direct and resonant PI. In the latter case, a remarkable behavior is observed which may be attributed to the interference occurring between undistinguishable autoionization decay channels.展开更多
文摘Spectroscopic characteristics of the β-fructosyltransferase(EC2.4.1.9 FTS) from Aspergillus oryzae GX0011 was studied by ultraviolet absorbance spectrum,fluorescence spectrum and circular dichroism.The enzyme exhibited that the characteristic peaks of ultraviolet absorbance spectrum,of fluorescence emission spectrum were at 280nm and 343nm.In low concentration of ,the fluorescence quenching was in line with the Sterm-Volmer’s equation and the percentage of Trp residue reacted by was 0.72.By comparing the fluorescence spectra of FTS substrate-perturbation,it was implied that some inner Trp residues participated in catalysis and might be involved in the active site of the enzyme.Furthermore,the secondary structures of FTS were quantitatively determined by circular dichroism.The relative percentage content of each secondary structure were:25.1±0.8% α-helix,5.3±2.3% β-sheet,31.4±1.5%β-turn and 38.2±1.1% random coil respectively.
文摘Molecular frame photoemission is a very sensitive probe of the photoionization （PI） dynamics of molecules. This paper reports a comparative study of non-resonant and resonant photoionization of D2 induced by VUV circularly polarized synchrotron radiation at SOLEIL at the level of the molecular frame photoelectron angular distributions （MFPADs）. We use the vector correlation method which combines imaging and time-of-flight resolved electron-ion coincidence techniques, and a generalized formalism for the expression of the Ⅰ（χ, θe, Фe） MFPADs, where χ is the orientation of the molecular axis with respect to the light quantization axis and （θe, Фe） the electron emission direction in the molecular frame. Selected MFPADs for a molecule aligned parallel or perpendicular to linearly polarized light, or perpendicular to the propagation axis of circularly polarized light, are presented for dissociative photoionization （DPI） of D2 at two photon excitation energies, hv=19 eV, where direct PI is the only channel opened, and hv=32.5 eV, i.e. in the region involving resonant excitation of Q1 and Q2 doubly excited state series. We discuss in particular the properties of the circular dichroism characterizing photoemission in the molecular frame for direct and resonant PI. In the latter case, a remarkable behavior is observed which may be attributed to the interference occurring between undistinguishable autoionization decay channels.
