Proteolysis is one of the most important biochemical reactions during cheese ripening.Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing ch...Proteolysis is one of the most important biochemical reactions during cheese ripening.Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing cheese quality.Fourier transform infrared spectroscopy(FTIR),with self-deconvolution,second derivative analysis and band curve-fitting,was used to characterize the secondary structure of proteins in Cheddar cheese during ripening.The spectra of the amide I region showed great similarity,while the relative contents of the secondary structures underwent a series of changes.As ripening progressed,the α-helix content decreased and the β-sheet content increased.This structural shift was attributed to the strengthening of hydrogen bonds that resulted from hydrolysis of caseins.In summary,FTIR could provide the basis for rapid characterization of cheese that is undergoing ripening.展开更多
Based on the starch hydrolysis reaction accelerated by microwave irradiation with α-amylase, the circular dichroism （CD） and secondary structure changes of α-amylase under the condition of microwave irradiation an...Based on the starch hydrolysis reaction accelerated by microwave irradiation with α-amylase, the circular dichroism （CD） and secondary structure changes of α-amylase under the condition of microwave irradiation and water bath were studied by circular dichroism spectra. The results showed that, both the peak heights （at 2=193 nm） of the CD spectra of the samples treated by microwave irradiation and water bath reduced. The reduced rate by microwave irradiation ranged from 140% to 220%, while the reduced rate by water bath ranged from 60% to 140%. The peak of the sample treated by microwave irradiation for 60 min disappeared at λ=193 nm, while the sample showed a wake peak by water bath. The peak position by microwave irradiation emerged a blue shift in the range of 5-8 nm at λ=204 nm and λ=220 nm, while it emerged in the range of 3-5 nm by water bath. With time going on, the microwave irradiation and water bath have prompted the secondary structure of α-helix, β-sheet, β-turn and the mutual transformations of random coil, but the trends were different.展开更多
Talin-1 head(hereinafter referred to as TH)is the head structure of talin protein,which contains a four-point-one-protein/ezrin/radixin/moesin(FERM)domain.Its F1 domain contains an unstructured loop of 30 amino acids(...Talin-1 head(hereinafter referred to as TH)is the head structure of talin protein,which contains a four-point-one-protein/ezrin/radixin/moesin(FERM)domain.Its F1 domain contains an unstructured loop of 30 amino acids(139-168),which does not interact with other domains.Because TH doesn’t get the crystal structure and whether the unstructured loop has obvious influence on the TH secondary structure,therefore,the truncated talin-1 headΔ139-168(hereinafter referred to as THΔ)was constructed and its structure and the impact of stability after truncation were analyzed.Molecular biology and structural biology methods were used to construct prokaryotic expression vectors of TH and THΔ,explore and optimize the expression conditions of recombinants,and they were purified by affinity chromatography and FPLC gel filtration chromatography.Finally,a large number of stable,high-purity protein samples were prepared successfully.The physicochemical properties and structural stability of the proteins were investigated by dynamic light scattering and circular dichroism.The results showed that the THΔsecondary structure of the truncated body did not change significantly,the structural stability was enhanced and the resistance to guanidine hydrochloride and high temperature was stronger.展开更多
基金financially supported by Beijing Municipal Commission of Education Co-Constructed Programand Chinese Universities Scientific Fund(2009-4-25)
文摘Proteolysis is one of the most important biochemical reactions during cheese ripening.Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing cheese quality.Fourier transform infrared spectroscopy(FTIR),with self-deconvolution,second derivative analysis and band curve-fitting,was used to characterize the secondary structure of proteins in Cheddar cheese during ripening.The spectra of the amide I region showed great similarity,while the relative contents of the secondary structures underwent a series of changes.As ripening progressed,the α-helix content decreased and the β-sheet content increased.This structural shift was attributed to the strengthening of hydrogen bonds that resulted from hydrolysis of caseins.In summary,FTIR could provide the basis for rapid characterization of cheese that is undergoing ripening.
基金Project(08A080) supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘Based on the starch hydrolysis reaction accelerated by microwave irradiation with α-amylase, the circular dichroism （CD） and secondary structure changes of α-amylase under the condition of microwave irradiation and water bath were studied by circular dichroism spectra. The results showed that, both the peak heights （at 2=193 nm） of the CD spectra of the samples treated by microwave irradiation and water bath reduced. The reduced rate by microwave irradiation ranged from 140% to 220%, while the reduced rate by water bath ranged from 60% to 140%. The peak of the sample treated by microwave irradiation for 60 min disappeared at λ=193 nm, while the sample showed a wake peak by water bath. The peak position by microwave irradiation emerged a blue shift in the range of 5-8 nm at λ=204 nm and λ=220 nm, while it emerged in the range of 3-5 nm by water bath. With time going on, the microwave irradiation and water bath have prompted the secondary structure of α-helix, β-sheet, β-turn and the mutual transformations of random coil, but the trends were different.
基金Supported by the Scientific Research Personnel of Northeast Agricultural University(518001)。
文摘Talin-1 head(hereinafter referred to as TH)is the head structure of talin protein,which contains a four-point-one-protein/ezrin/radixin/moesin(FERM)domain.Its F1 domain contains an unstructured loop of 30 amino acids(139-168),which does not interact with other domains.Because TH doesn’t get the crystal structure and whether the unstructured loop has obvious influence on the TH secondary structure,therefore,the truncated talin-1 headΔ139-168(hereinafter referred to as THΔ)was constructed and its structure and the impact of stability after truncation were analyzed.Molecular biology and structural biology methods were used to construct prokaryotic expression vectors of TH and THΔ,explore and optimize the expression conditions of recombinants,and they were purified by affinity chromatography and FPLC gel filtration chromatography.Finally,a large number of stable,high-purity protein samples were prepared successfully.The physicochemical properties and structural stability of the proteins were investigated by dynamic light scattering and circular dichroism.The results showed that the THΔsecondary structure of the truncated body did not change significantly,the structural stability was enhanced and the resistance to guanidine hydrochloride and high temperature was stronger.
