In this paper, the poling properties of (PS)O-DCV, a derivative of poly (p-hydroxystyrene ), was reported. The investigations showed that the thermochromism correction, which was neglected in the literatures, should b...In this paper, the poling properties of (PS)O-DCV, a derivative of poly (p-hydroxystyrene ), was reported. The investigations showed that the thermochromism correction, which was neglected in the literatures, should be considered in the measurements of order parameter of poled films with electrochromism technique Here, another linear optical method, IR and polarized IR spectra for characterizing of poled films was suggested first time. The bulk second nonlinear optical coefficient d_(33) of poled films could be estimated by measured order parameter semi-qualitatively.展开更多
Hyaluronan is a kind of polysaccharide with high molecule weight, hs structure is relatively complicated and tertiary structure exists among the HA molecules when reaching to o certain solution concentration . FT- IR ...Hyaluronan is a kind of polysaccharide with high molecule weight, hs structure is relatively complicated and tertiary structure exists among the HA molecules when reaching to o certain solution concentration . FT- IR spectrum has been acquired to shou the groups and their ascription in HA. The results of FT-IR spectrum in this essay accords well with that issued by ASTM. As to the newly appearing absorption peaks, sensible explanation has been given, In ADDITION , Ramon spectrum has been employed as a proof for the result of the FT-IR spectnun. Based on the preliminary acknowledge of the functional groups in HA, circular dichroism of the material has also been explored.展开更多
Otamixaban is a potent (Ki=0.5 nM) fXa inhibitor currently in late-stage clinical develop-ment at Sanofi for the management of acute coronary syndrome. Being unproductive in obtaining a suitable crystal of Otamixaba...Otamixaban is a potent (Ki=0.5 nM) fXa inhibitor currently in late-stage clinical develop-ment at Sanofi for the management of acute coronary syndrome. Being unproductive in obtaining a suitable crystal of Otamixaban, the required enantiomeric characterization has been accomplished using vibrational circular dichroism (VCD) spectroscopy. Selected by a spectrum similarity index, the calculated spectra of several higher energy conformers were found to match well with the observed spectra. The characteristic IR bands of these conformers were also identified and attributed to the solvation effect. Combined with both the single crystal x-ray diffraction results for an intermediate and the proton NMR study, the absolute configuration of Otamixaban is unambiguously determined to be (R,R).展开更多
<span style="font-family:Verdana;">Glycine crystallizes into three different polymorphs called </span><i><span style="font-family:Verdana;">α</span></i><span...<span style="font-family:Verdana;">Glycine crystallizes into three different polymorphs called </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;"> under standard physicochemical conditions. They have different features depending on their structural variations. The possible interaction of glycine with magnetic minerals in meteorites and comets or in the ancient Earth, paves the way to study the self-assembly and molecular behavior under irradiation and magnetic conditions. The magnetic field might induce the formation of a specific polymorph of glycine. To gain insight on the consequences of gamma irradiation with a gradient of static magnetic fields (0.06 T, 0.3 T, 0.42 T and 0.6 T) on the self-assembly of single macroscopic glycine crystals, we gamma irradiated the powdered amino acid and then assembled single crystals from water solutions. The preliminary results showed a stable formation of fluid </span><span style="font-family:Verdana;">inclusions in the single crystals and no straightforward effect on the</span><span style="font-family:Verdana;"> self-assem</span><span style="font-family:Verdana;">- </span><span style="font-family:;" "=""><span style="font-family:Verdana;">bly process after glycine gamma irradiation and interaction with static magnetic fields. The </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;"> glycine polymorph single crystals formed at 55<span style="white-space:nowrap;">°</span> from the magnetic longitudinal axis and seemed to be enhanced by gamma radiation. </span><span><span style="font-family:Verdana;">The </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;">-glycine single crystals presented L and D circular dichroism signals,</span></span><span style="font-family:Verdana;"> whereas the irradiated samples presented no circular dichroism bands. Com</span></span><span style="font-family:Verdana;">- </span><span style="font-family:;" "=""><span style="font-family:Verdana;">puter simulations suggest different catalytic properties from </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;"> glycine crystals.</span></span>展开更多
Hydrophobic mismatch between the hydrophobic length of membrane proteins and hydrophobic thickness of membranes is a crucial factor in controlling protein function and assembly.We combined fluorescence with circular d...Hydrophobic mismatch between the hydrophobic length of membrane proteins and hydrophobic thickness of membranes is a crucial factor in controlling protein function and assembly.We combined fluorescence with circular dichroism(CD) and attenuated total reflection infrared(ATR-IR) spectroscopic methods to investigate the behaviors of the peptide and lipids under hydrophobic mismatch using a model peptide from the fourth transmembrane domain of natural resistance-associated macrophage protein 1(Nramp1),the phosphatidylcholines(PCs) and phosphatidylglycerols(PGs) with different lengths of acyl chains(14:0,16:0 and 18:0).In all PG lipid membranes,the peptide forms stable α-helix structure,and the helix axis is parallel to lipid chains.The helical span and orientation hardly change in varying thickness of PG membranes,while the lipid chains can deform to accommodate to the hydrophobic surface of embedded peptide.By comparison,the helical structures of the model peptide in PC lipid membranes are less stable.Upon incorporation with PC lipid membranes,the peptide can deform itself to accommodate to the hydrophobic thickness of lipid membranes in response to hydrophobic mismatch.In addition,hydrophobic mismatch can increase the aggregation propensity of the peptide in both PC and PG lipid membranes and the peptide in PC membranes has more aggregation tendency than that in PG membranes.展开更多
The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrar...The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Molecular docking was performed to reveal the possible binding mode or mechanism and suggested that guaiacol can strongly bind to human immu- noglobulin (HIgG). It is considered that guaiacol binds to HIgG mainly by a hydrophobic interaction and there are two hydrogen bond interactions between the drug and the residues LEU 80 and ASP 65, which is in good agreement with the results from the experimental thermodynamic parameters (the enthalpy change △H0 and the entropy change △S0 were calculated to be 65.55 kJ·mol-1 and 132.95 J·mol-1·K-1 according to the Vant’ Hoff equation). Data obtained by the fluorescence spectroscopy indicated that binding of guaiacol with HIgG leads to dramatic enhancement in the fluorescence emission intensity along with significant occurrence of efficient Frster resonance energy transfer (FRET) from the residue of HIgG to the protein bound guaiacol. From the low value of fluorescence anisotropy (r = 0.06), it is argued that the probe molecule is located in the motionally unrestricted environment of the protein. The alterations of protein’s secondary structure in the presence of guaiacol in aqueous solution were quantitatively calculated by the evidences from FT-IR and CD spectroscopes.展开更多
Fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) and FT-Raman spectroscopy were employed to analyze the binding of the asiatic acid (AA) to bovine serum albumin...Fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) and FT-Raman spectroscopy were employed to analyze the binding of the asiatic acid (AA) to bovine serum albumin (BSA) under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by AA was the result of the formation of BSA-AA complex. The fluorescence quenching mechanism of BSA by AA was a static quenching procedure. According to the Van't Hoff equation, the thermodynamic parameters enthalpy change (△H0) and entropy change (△S0) for the reaction were evaluated to be --12.55 kJ·mol^-1 and 67.08 kJomol 1, respectively, indicating that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The influence of AA on the conformation of BSA has also been analyzed on the basis of FT-IR, CD and FT-Raman spectra.展开更多
文摘In this paper, the poling properties of (PS)O-DCV, a derivative of poly (p-hydroxystyrene ), was reported. The investigations showed that the thermochromism correction, which was neglected in the literatures, should be considered in the measurements of order parameter of poled films with electrochromism technique Here, another linear optical method, IR and polarized IR spectra for characterizing of poled films was suggested first time. The bulk second nonlinear optical coefficient d_(33) of poled films could be estimated by measured order parameter semi-qualitatively.
文摘Hyaluronan is a kind of polysaccharide with high molecule weight, hs structure is relatively complicated and tertiary structure exists among the HA molecules when reaching to o certain solution concentration . FT- IR spectrum has been acquired to shou the groups and their ascription in HA. The results of FT-IR spectrum in this essay accords well with that issued by ASTM. As to the newly appearing absorption peaks, sensible explanation has been given, In ADDITION , Ramon spectrum has been employed as a proof for the result of the FT-IR spectnun. Based on the preliminary acknowledge of the functional groups in HA, circular dichroism of the material has also been explored.
文摘Otamixaban is a potent (Ki=0.5 nM) fXa inhibitor currently in late-stage clinical develop-ment at Sanofi for the management of acute coronary syndrome. Being unproductive in obtaining a suitable crystal of Otamixaban, the required enantiomeric characterization has been accomplished using vibrational circular dichroism (VCD) spectroscopy. Selected by a spectrum similarity index, the calculated spectra of several higher energy conformers were found to match well with the observed spectra. The characteristic IR bands of these conformers were also identified and attributed to the solvation effect. Combined with both the single crystal x-ray diffraction results for an intermediate and the proton NMR study, the absolute configuration of Otamixaban is unambiguously determined to be (R,R).
文摘<span style="font-family:Verdana;">Glycine crystallizes into three different polymorphs called </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;"> under standard physicochemical conditions. They have different features depending on their structural variations. The possible interaction of glycine with magnetic minerals in meteorites and comets or in the ancient Earth, paves the way to study the self-assembly and molecular behavior under irradiation and magnetic conditions. The magnetic field might induce the formation of a specific polymorph of glycine. To gain insight on the consequences of gamma irradiation with a gradient of static magnetic fields (0.06 T, 0.3 T, 0.42 T and 0.6 T) on the self-assembly of single macroscopic glycine crystals, we gamma irradiated the powdered amino acid and then assembled single crystals from water solutions. The preliminary results showed a stable formation of fluid </span><span style="font-family:Verdana;">inclusions in the single crystals and no straightforward effect on the</span><span style="font-family:Verdana;"> self-assem</span><span style="font-family:Verdana;">- </span><span style="font-family:;" "=""><span style="font-family:Verdana;">bly process after glycine gamma irradiation and interaction with static magnetic fields. The </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;"> glycine polymorph single crystals formed at 55<span style="white-space:nowrap;">°</span> from the magnetic longitudinal axis and seemed to be enhanced by gamma radiation. </span><span><span style="font-family:Verdana;">The </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;">-glycine single crystals presented L and D circular dichroism signals,</span></span><span style="font-family:Verdana;"> whereas the irradiated samples presented no circular dichroism bands. Com</span></span><span style="font-family:Verdana;">- </span><span style="font-family:;" "=""><span style="font-family:Verdana;">puter simulations suggest different catalytic properties from </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;"> glycine crystals.</span></span>
基金Supported by the National Natural Science Foundation of China(Nos.20973083,20934002)
文摘Hydrophobic mismatch between the hydrophobic length of membrane proteins and hydrophobic thickness of membranes is a crucial factor in controlling protein function and assembly.We combined fluorescence with circular dichroism(CD) and attenuated total reflection infrared(ATR-IR) spectroscopic methods to investigate the behaviors of the peptide and lipids under hydrophobic mismatch using a model peptide from the fourth transmembrane domain of natural resistance-associated macrophage protein 1(Nramp1),the phosphatidylcholines(PCs) and phosphatidylglycerols(PGs) with different lengths of acyl chains(14:0,16:0 and 18:0).In all PG lipid membranes,the peptide forms stable α-helix structure,and the helix axis is parallel to lipid chains.The helical span and orientation hardly change in varying thickness of PG membranes,while the lipid chains can deform to accommodate to the hydrophobic surface of embedded peptide.By comparison,the helical structures of the model peptide in PC lipid membranes are less stable.Upon incorporation with PC lipid membranes,the peptide can deform itself to accommodate to the hydrophobic thickness of lipid membranes in response to hydrophobic mismatch.In addition,hydrophobic mismatch can increase the aggregation propensity of the peptide in both PC and PG lipid membranes and the peptide in PC membranes has more aggregation tendency than that in PG membranes.
文摘The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Molecular docking was performed to reveal the possible binding mode or mechanism and suggested that guaiacol can strongly bind to human immu- noglobulin (HIgG). It is considered that guaiacol binds to HIgG mainly by a hydrophobic interaction and there are two hydrogen bond interactions between the drug and the residues LEU 80 and ASP 65, which is in good agreement with the results from the experimental thermodynamic parameters (the enthalpy change △H0 and the entropy change △S0 were calculated to be 65.55 kJ·mol-1 and 132.95 J·mol-1·K-1 according to the Vant’ Hoff equation). Data obtained by the fluorescence spectroscopy indicated that binding of guaiacol with HIgG leads to dramatic enhancement in the fluorescence emission intensity along with significant occurrence of efficient Frster resonance energy transfer (FRET) from the residue of HIgG to the protein bound guaiacol. From the low value of fluorescence anisotropy (r = 0.06), it is argued that the probe molecule is located in the motionally unrestricted environment of the protein. The alterations of protein’s secondary structure in the presence of guaiacol in aqueous solution were quantitatively calculated by the evidences from FT-IR and CD spectroscopes.
基金Project supported by the National Natural Science Foundation of China (Nos. 20671023, 30460153, 21061002), the Key Project of Chinese Ministry of Education (Nos. 03101, 204111), Guangxi Natural Science Foundation of China (No. 2010GXNSFF013001), and the Innovation Project of Guangxi Graduate Education (No. 2009106020703M42).
文摘Fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) and FT-Raman spectroscopy were employed to analyze the binding of the asiatic acid (AA) to bovine serum albumin (BSA) under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by AA was the result of the formation of BSA-AA complex. The fluorescence quenching mechanism of BSA by AA was a static quenching procedure. According to the Van't Hoff equation, the thermodynamic parameters enthalpy change (△H0) and entropy change (△S0) for the reaction were evaluated to be --12.55 kJ·mol^-1 and 67.08 kJomol 1, respectively, indicating that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The influence of AA on the conformation of BSA has also been analyzed on the basis of FT-IR, CD and FT-Raman spectra.