Chirality hold broad applications in life sciences,quantum devices,and various other areas.Traditionally,molecular chirality can be characterized by using steady-state circular dichroism spectroscopy.However,the techn...Chirality hold broad applications in life sciences,quantum devices,and various other areas.Traditionally,molecular chirality can be characterized by using steady-state circular dichroism spectroscopy.However,the techniques that can characterize excited state chirality are progressively capturing the public interest as it can provide the dynamic information for chirality generation and transfer.In this review,we focus on the theoretical background and the developmental history of femtosecond time-resolved circular dichroism spectroscopy(TRCD)techniques around the world.Additionally,we provide examples to showcase the utility of these techniques in the analysis of the dynamical molecular chemical structures,the investigation of molecular chirality generation,and the detection of electron spin dynamics in semiconductor quantum dots.展开更多
The effects of temperature,pH and long-term storage on the secondary structure and conformation changes of bovine haemoglobin（bHb） were studied using circular dichroism（CD） and ultraviolet-visible（UV-vis） spectr...The effects of temperature,pH and long-term storage on the secondary structure and conformation changes of bovine haemoglobin（bHb） were studied using circular dichroism（CD） and ultraviolet-visible（UV-vis） spectroscopies.Neural network software was used to deconvolute the CD data to obtain the fractional content of the five secondary structures.The storage stability of bHb solutions in pH 6,7 and8 buffers was significantly higher at 4 ℃ than at 23 ℃ for the first 3 days.A complete denaturation of bHb was observed after 40 days irrespective of storage temperature or pH.The bHb solutions were also exposed to heating and cooling cycles between 25 and 65 ℃ and structural changes were followed by UVvis and CD spectroscopies.These experiments demonstrated that α-helix content of bHb decreased steadily with the increasing temperature above 35 ℃ at all pH values.The loss in a-helicity and gain in random coil conformations was pH-dependent and the greatest under alkaline conditions.Furthermore,there was minimal recovery of the secondary structure content upon cooling to 25 ℃.The use of bHb as a model drug is very common and this study elucidates the significance of storage and processing conditions on its stability.展开更多
In human cells, the heterogeneous nuclear ribonucleoproteins (hnRNP) are represented by a group of polypeptides, with various molecular properties, comprizing the most abundant constituents of the cell nucleus. Autoan...In human cells, the heterogeneous nuclear ribonucleoproteins (hnRNP) are represented by a group of polypeptides, with various molecular properties, comprizing the most abundant constituents of the cell nucleus. Autoantibodies to hnRNPs have been reported in patients suffering from different rheumatic dieseases since 1980s. Experimental evidence indicates that hnRNP complexes undergo substantial structural changes during mRNA formation and export. However, how this contributes to disease development still has to be elucidated. Here some preliminary physicochemical features of RNA-protein folding and stability patterns of newly characterized hnRNP A3 with further functional implications in development of systemic human autoimmune states are reported.展开更多
Two new chiral Schiff base acacen-derivative nickel（II） and copper（II） complexes have been prepared and characterized with IR, electronic, and CD spectra and X-ray crystallography. So-called artifact peaks of soli...Two new chiral Schiff base acacen-derivative nickel（II） and copper（II） complexes have been prepared and characterized with IR, electronic, and CD spectra and X-ray crystallography. So-called artifact peaks of solid-state CD spectra due to restricted to rotate freely of molecules appeared at about 334 and 460 nm for nickel（II） and copper（II） complexes. Changes of intensity of the peaks have been investigated in different matrices such as solid-state （microcrystals or KBr pellets）, PMMA cast films and acetone solutions of various concentrations and pure acetone solutions. Although restricted orientation of molecules in rigid matrices leads to increase the peak intensity toward negative and positive optical rotation for nickel（II） and copper（II） complexes, respectively, the degree of increasing intensity depends on not concentration but viscosity of polymer solutions. Therefore, the artifact CD peaks of solid-state can act as an indicator of environmental viscosity of soft mater matrices.展开更多
Chirality,defined by Lord Kelvin,refers to the geometric symmetry property of an object that cannot be superposed onto its mirror image using rotations and translations.The material’s chirality can be probed with lig...Chirality,defined by Lord Kelvin,refers to the geometric symmetry property of an object that cannot be superposed onto its mirror image using rotations and translations.The material’s chirality can be probed with light as the optical activity:optical rotary dispersion(ORD)and circular dichroism(CD).It is still challenging to yield extremely sensitive ORD and CD for very weak chirality and measure both simultaneously.Cavity ringdown polarimetry has been reported to improve ORD detection sensitivity with the absence of equally important CD signature,at the price of high cavity finesse near 400,frequency-locking sophistication,and large magnetic field.Here,we report a unique recipe to demonstrate the simultaneous measurement of ORD and the CD by separately observing the chiral eigenmode spectra from a bowtie optical cavity with a finesse about 30,without resorting to frequency locking or magnetic field.We obtain a sensitivity of2.7×10^(−3)deg/√Hz for ORD,8.1×10^(−6)/√Hz for CD,and a spectral resolution of 0.04 pm within a millisecond-scale measurement.We present a cost-effective yet ultrasensitive account for chiral chromatography,the conformational dynamics and chiroptical analysis of biological samples which particularly exhibit weak and narrow spectral signals.展开更多
The interaction of raltitrexed（RTX） with bovine serum albumin（BSA） was investigated by steady state/lifetime fluorescence spectroscopy and circular dichroism（CD） spectroscopy under the simulative physiological c...The interaction of raltitrexed（RTX） with bovine serum albumin（BSA） was investigated by steady state/lifetime fluorescence spectroscopy and circular dichroism（CD） spectroscopy under the simulative physiological conditions.The results of fluorescence titration reveal that RTX could strongly quench the intrinsic fluorescence of BSA via a static quenching procedure.The obtained binding constant K A of RTX with BSA was 478630 and 44259 L/mol at 298 and 310 K,respectively.According to van＇t Hoff equation,the thermodynamic parameters ΔH,ΔG and ΔS were calculated,indicating that hydrophobic forces were the predominant intermolecular forces in stabilizing the complex.The binding process was a spontaneous process,in which Gibbs free energy change was negative.According to F rster＇s non-radioactive energy transfer theory,the distance r between donor（BSA） and acceptor（RTX） was 3.82 nm,suggesting that the energy transfer from BSA to RTX occurred with high probability.Displacement experiment and the number of binding sites calculation confirmed that RTX could bind to the site-I of BSA.Furthermore,the effects of pH and some metal ions on the interaction of RTX with BSA were also investigated.The results of synchronous fluorescence and CD spectra show that the RTX-BSA binding induced conformational changes in BSA.展开更多
Chromomycin A3 (CHR, pKa = 7.0), an aureolic acid group of antitumor antibiotic, undergoes self-association in aqueous solution in neutral and anionic forms. Self-association processes of neutral and anionic CHR have ...Chromomycin A3 (CHR, pKa = 7.0), an aureolic acid group of antitumor antibiotic, undergoes self-association in aqueous solution in neutral and anionic forms. Self-association processes of neutral and anionic CHR have been studied in pH 5.0 and pH 9.0, respectively using different spectroscopic methods such as absorbance, fluorescence, CD, NMR and isothermal titration calorimetry (ITC). Results from these studies reveal that at low concentration (2 + CHR (CHR)3 and (CHR)3 + CHR (CHR)4. Analysis of NMR spectra of 100 μM and 1 mM CHR indicates that the self-association of CHR (neutral and anionic form) is most likely to happen via hydrophobic interaction involving the sugar moieties and surrounding water molecules. Calorimetric studies indicate that self-association of both anionic and neutral CHR is entropy driven. These observations imply that sugar substituents play a major role in their state of aggregation after biosynthesis from a gene cluster. The self-association features of the antibiotic have been compared with those of Mithramycin, an antibiotic of the same group.展开更多
The alkali-hydrolysis of D-glucono-delta-lactone (GDL) was investigated by chiral Raman and circular dichroism (CD) spectroscopies in combination with density functional theory calculation. Based on the characteristic...The alkali-hydrolysis of D-glucono-delta-lactone (GDL) was investigated by chiral Raman and circular dichroism (CD) spectroscopies in combination with density functional theory calculation. Based on the characteristic CD bands of GDL and its hydrolysis product, the dynamics of hydrolysis was studied using stopped-flow CD method. Using chiral Raman spectroscopy (CRS), the stereochemical change of GDL owing to the hydrolysis reaction was discussed on the vibrational scale. The CRS results show that the ring-opening due to hydrolysis has a great influence on the chiral structure around the car-bonyl group, which was evidenced by the disappearance of the CRS band at 1735 cm-1 (C== O stretching vibrational mode). In addition, the change of positions and intensity of CRS bands was also observed, which was ascribed to the perturbation around the C2, C3, C4 and C5 carbons due to ring-opening. It is worthy to note that the stereochemistry of C2, C3, C4 and C5 had no fundamental change during the hydrolysis reaction, which was reflected in the maintenance of the signs of the CRS bands. Our results demonstrate that in comparison with CD technique, CRS may provide more detailed structural information of chiral molecules and open up new vistas of research for chiral reactions.展开更多
Circular dichroism spectroscopy can be optimized to measure the scattering circular dichroism response of a single chiral nanostructure with a single shot.
基金funded by the National Natural Science Foundation of China(No.92156024and No.92356307 to Jinquan Chen)Menghui Jia thanks the Materials Characterization Center and the Office of Laboratory and Equipment of East China Normal University for funding support(ECNUETR2023-13).
文摘Chirality hold broad applications in life sciences,quantum devices,and various other areas.Traditionally,molecular chirality can be characterized by using steady-state circular dichroism spectroscopy.However,the techniques that can characterize excited state chirality are progressively capturing the public interest as it can provide the dynamic information for chirality generation and transfer.In this review,we focus on the theoretical background and the developmental history of femtosecond time-resolved circular dichroism spectroscopy(TRCD)techniques around the world.Additionally,we provide examples to showcase the utility of these techniques in the analysis of the dynamical molecular chemical structures,the investigation of molecular chirality generation,and the detection of electron spin dynamics in semiconductor quantum dots.
基金the University of Greenwich for financial support
文摘The effects of temperature,pH and long-term storage on the secondary structure and conformation changes of bovine haemoglobin（bHb） were studied using circular dichroism（CD） and ultraviolet-visible（UV-vis） spectroscopies.Neural network software was used to deconvolute the CD data to obtain the fractional content of the five secondary structures.The storage stability of bHb solutions in pH 6,7 and8 buffers was significantly higher at 4 ℃ than at 23 ℃ for the first 3 days.A complete denaturation of bHb was observed after 40 days irrespective of storage temperature or pH.The bHb solutions were also exposed to heating and cooling cycles between 25 and 65 ℃ and structural changes were followed by UVvis and CD spectroscopies.These experiments demonstrated that α-helix content of bHb decreased steadily with the increasing temperature above 35 ℃ at all pH values.The loss in a-helicity and gain in random coil conformations was pH-dependent and the greatest under alkaline conditions.Furthermore,there was minimal recovery of the secondary structure content upon cooling to 25 ℃.The use of bHb as a model drug is very common and this study elucidates the significance of storage and processing conditions on its stability.
文摘In human cells, the heterogeneous nuclear ribonucleoproteins (hnRNP) are represented by a group of polypeptides, with various molecular properties, comprizing the most abundant constituents of the cell nucleus. Autoantibodies to hnRNPs have been reported in patients suffering from different rheumatic dieseases since 1980s. Experimental evidence indicates that hnRNP complexes undergo substantial structural changes during mRNA formation and export. However, how this contributes to disease development still has to be elucidated. Here some preliminary physicochemical features of RNA-protein folding and stability patterns of newly characterized hnRNP A3 with further functional implications in development of systemic human autoimmune states are reported.
文摘Two new chiral Schiff base acacen-derivative nickel（II） and copper（II） complexes have been prepared and characterized with IR, electronic, and CD spectra and X-ray crystallography. So-called artifact peaks of solid-state CD spectra due to restricted to rotate freely of molecules appeared at about 334 and 460 nm for nickel（II） and copper（II） complexes. Changes of intensity of the peaks have been investigated in different matrices such as solid-state （microcrystals or KBr pellets）, PMMA cast films and acetone solutions of various concentrations and pure acetone solutions. Although restricted orientation of molecules in rigid matrices leads to increase the peak intensity toward negative and positive optical rotation for nickel（II） and copper（II） complexes, respectively, the degree of increasing intensity depends on not concentration but viscosity of polymer solutions. Therefore, the artifact CD peaks of solid-state can act as an indicator of environmental viscosity of soft mater matrices.
基金supported by the National Key R&D Program of China(Grants No.2022YFA1405000,No.2019YFA0308700)the National Natural Science Foundation of China(Grants No.92365107,No.12305020,and No.11890704)+5 种基金the Program for Innovative Talents and Teams in Jiangsu(Grant No.JSSCTD202138)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301400)China Postdoctoral Science Foundation(Grant No.2023M731613)Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2023ZB708)C.-W.Q.is supported by the Competitive Research Program Award(NRF-CRP22-2019-0006&NRF-CRP26-2021-0004)from the NRF,Prime Minister’s Office,Singaporeby a grant(A-0005947-16-00)from A*STAR MTC IRG(M22K2c0088 with A-8001322-00-00).
文摘Chirality,defined by Lord Kelvin,refers to the geometric symmetry property of an object that cannot be superposed onto its mirror image using rotations and translations.The material’s chirality can be probed with light as the optical activity:optical rotary dispersion(ORD)and circular dichroism(CD).It is still challenging to yield extremely sensitive ORD and CD for very weak chirality and measure both simultaneously.Cavity ringdown polarimetry has been reported to improve ORD detection sensitivity with the absence of equally important CD signature,at the price of high cavity finesse near 400,frequency-locking sophistication,and large magnetic field.Here,we report a unique recipe to demonstrate the simultaneous measurement of ORD and the CD by separately observing the chiral eigenmode spectra from a bowtie optical cavity with a finesse about 30,without resorting to frequency locking or magnetic field.We obtain a sensitivity of2.7×10^(−3)deg/√Hz for ORD,8.1×10^(−6)/√Hz for CD,and a spectral resolution of 0.04 pm within a millisecond-scale measurement.We present a cost-effective yet ultrasensitive account for chiral chromatography,the conformational dynamics and chiroptical analysis of biological samples which particularly exhibit weak and narrow spectral signals.
基金Supported by the National Natural Science Foundation of China(No.30973659)
文摘The interaction of raltitrexed（RTX） with bovine serum albumin（BSA） was investigated by steady state/lifetime fluorescence spectroscopy and circular dichroism（CD） spectroscopy under the simulative physiological conditions.The results of fluorescence titration reveal that RTX could strongly quench the intrinsic fluorescence of BSA via a static quenching procedure.The obtained binding constant K A of RTX with BSA was 478630 and 44259 L/mol at 298 and 310 K,respectively.According to van＇t Hoff equation,the thermodynamic parameters ΔH,ΔG and ΔS were calculated,indicating that hydrophobic forces were the predominant intermolecular forces in stabilizing the complex.The binding process was a spontaneous process,in which Gibbs free energy change was negative.According to F rster＇s non-radioactive energy transfer theory,the distance r between donor（BSA） and acceptor（RTX） was 3.82 nm,suggesting that the energy transfer from BSA to RTX occurred with high probability.Displacement experiment and the number of binding sites calculation confirmed that RTX could bind to the site-I of BSA.Furthermore,the effects of pH and some metal ions on the interaction of RTX with BSA were also investigated.The results of synchronous fluorescence and CD spectra show that the RTX-BSA binding induced conformational changes in BSA.
文摘Chromomycin A3 (CHR, pKa = 7.0), an aureolic acid group of antitumor antibiotic, undergoes self-association in aqueous solution in neutral and anionic forms. Self-association processes of neutral and anionic CHR have been studied in pH 5.0 and pH 9.0, respectively using different spectroscopic methods such as absorbance, fluorescence, CD, NMR and isothermal titration calorimetry (ITC). Results from these studies reveal that at low concentration (2 + CHR (CHR)3 and (CHR)3 + CHR (CHR)4. Analysis of NMR spectra of 100 μM and 1 mM CHR indicates that the self-association of CHR (neutral and anionic form) is most likely to happen via hydrophobic interaction involving the sugar moieties and surrounding water molecules. Calorimetric studies indicate that self-association of both anionic and neutral CHR is entropy driven. These observations imply that sugar substituents play a major role in their state of aggregation after biosynthesis from a gene cluster. The self-association features of the antibiotic have been compared with those of Mithramycin, an antibiotic of the same group.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20621063, 20773123, and 20673110)Programme for Strategic Scientific Alli-ances between China and the Netherlands (Grant No. 2008DFB50130)
文摘The alkali-hydrolysis of D-glucono-delta-lactone (GDL) was investigated by chiral Raman and circular dichroism (CD) spectroscopies in combination with density functional theory calculation. Based on the characteristic CD bands of GDL and its hydrolysis product, the dynamics of hydrolysis was studied using stopped-flow CD method. Using chiral Raman spectroscopy (CRS), the stereochemical change of GDL owing to the hydrolysis reaction was discussed on the vibrational scale. The CRS results show that the ring-opening due to hydrolysis has a great influence on the chiral structure around the car-bonyl group, which was evidenced by the disappearance of the CRS band at 1735 cm-1 (C== O stretching vibrational mode). In addition, the change of positions and intensity of CRS bands was also observed, which was ascribed to the perturbation around the C2, C3, C4 and C5 carbons due to ring-opening. It is worthy to note that the stereochemistry of C2, C3, C4 and C5 had no fundamental change during the hydrolysis reaction, which was reflected in the maintenance of the signs of the CRS bands. Our results demonstrate that in comparison with CD technique, CRS may provide more detailed structural information of chiral molecules and open up new vistas of research for chiral reactions.
文摘Circular dichroism spectroscopy can be optimized to measure the scattering circular dichroism response of a single chiral nanostructure with a single shot.
