Using gel chromatography of Sephadex G-75 superfine connectedwith Sephadex G-50 fine column,three human γ- crystallins(γ1,γ2,γ3)couldbe obtained.Seven agglutinins(LCA,SBA,DBA,PNA,BSL,RCA and UEA)were used to detec...Using gel chromatography of Sephadex G-75 superfine connectedwith Sephadex G-50 fine column,three human γ- crystallins(γ1,γ2,γ3)couldbe obtained.Seven agglutinins(LCA,SBA,DBA,PNA,BSL,RCA and UEA)were used to detect the sugar of sub-γ-crystallins,which had been transferredto nitrocellulose membrane and finally stained with ABC reagents and the sub-strate of HPR.These results suggested that γ2-and γ3-crystallin contain sugar,but γ1-crystallin has no sugar.There is a decrease of carbohydrate of γ2 and γ3as...展开更多
γ_1-γ_2-and γ_3-crystallin(corresponding to γs-,γC-and γD- crys-tallin respectively)of human fetal,2 year and 20^+ year old lenses areseparated by Sephadex gel chromatography.lodide and acrylamide are usedto que...γ_1-γ_2-and γ_3-crystallin(corresponding to γs-,γC-and γD- crys-tallin respectively)of human fetal,2 year and 20^+ year old lenses areseparated by Sephadex gel chromatography.lodide and acrylamide are usedto quench the tryptophane fluorescence of sub-γ-crystalline fractions and Ksvand fa values are calculated.The results show that iodide has no clear quench-ing effects on all γ-crystallins,the quenching effects of acrylamide on the tryp-tophan fluorescences of γ1-γ2-and γ3-crystallin from lenses of the ...展开更多
The pore formation mechanism of β-crystalline polypropylene under stretching was investigated. The porosity of the samples increases rapidly with stretching, having a maximum at draw ratios around 2 and then decrease...The pore formation mechanism of β-crystalline polypropylene under stretching was investigated. The porosity of the samples increases rapidly with stretching, having a maximum at draw ratios around 2 and then decreases monotonically. An abrupt formation process of initial micropores at very low draw ratios was evidenced by in situ SAXS measurements. At the same time the phase transition from β-crystal to α-crystal proceeds slowly in the whole deformation process up to large draw ratios around 5. Comparative studies of α-and β-crystalline polypropylene samples before stretching indicate that in addition to difference in crystal forms the α-and β-crystalline polypropylene samples exhibit quite different morphological features. There are a lot of interfaces in β-crystalline polypropylene samples, which may have a lower density value and can be easily etched by argon ions and penetrated by small molecules. It was concluded from these experimental facts that the pore formation and crystal transition are two independent phenomena during the deformation of β-crystalline polypropylene samples, and phase transition from β-crystal to α-crystal could hardly be the origin of pore formation. A defect initiation mechanism was proposed to understand the pore formation behavior of β-crystalline polypropylenes.展开更多
Differential scanning calorimetry and X-ray diffraction experiments on β-nucleated polypropylene were made on the samples crystallized at different temperatures and processed by injection molding. The crystal perfect...Differential scanning calorimetry and X-ray diffraction experiments on β-nucleated polypropylene were made on the samples crystallized at different temperatures and processed by injection molding. The crystal perfection was shown to vary with crystallization temperature. The observed multiple peaks could be related to a ill-phase with defective inclination of the chains, a recrystallized or original β_2-phase of more perfect inclination, and the α-phase. Injection molded samples could be analyzed from the established DSC interpretation.展开更多
a-Crystallin is the major structural protein of eye lens of vertebrates. In human lens, the ratio of aA-crystallin to aB-crystallin was found to be 3:1. aA-Crystallin contains two cysteine residues at positions 131 an...a-Crystallin is the major structural protein of eye lens of vertebrates. In human lens, the ratio of aA-crystallin to aB-crystallin was found to be 3:1. aA-Crystallin contains two cysteine residues at positions 131 and 142, which are at the junction between the a-crystallin domain and the C-terminal tail. We used the accessibility of the thiol groups by Ellman’s reagent (DTNB) as a tool to gain information about the various structural perturbations of hinge region of a-crystallin and during the binding with substrates. In the native condition, the cys-142 though reacted quite fast was not fully exposed. Several reagents were used to see the accessibility of cys-131. Rate constant for cys-131 was increased gradually with increase in the concentration of reagents. The bindings of substrates are affected by the accessibility of thiol indicating that the substrates bind to the hinge region of a-crystallin. By blocking of cys-142, it was observed that the accessibility of one thiol depends on the other thiol, and they are not independent. The hinge region of a-crystallin is very important as substrate binding site and from this study we have got various structural information about that region.展开更多
文摘Using gel chromatography of Sephadex G-75 superfine connectedwith Sephadex G-50 fine column,three human γ- crystallins(γ1,γ2,γ3)couldbe obtained.Seven agglutinins(LCA,SBA,DBA,PNA,BSL,RCA and UEA)were used to detect the sugar of sub-γ-crystallins,which had been transferredto nitrocellulose membrane and finally stained with ABC reagents and the sub-strate of HPR.These results suggested that γ2-and γ3-crystallin contain sugar,but γ1-crystallin has no sugar.There is a decrease of carbohydrate of γ2 and γ3as...
文摘γ_1-γ_2-and γ_3-crystallin(corresponding to γs-,γC-and γD- crys-tallin respectively)of human fetal,2 year and 20^+ year old lenses areseparated by Sephadex gel chromatography.lodide and acrylamide are usedto quench the tryptophane fluorescence of sub-γ-crystalline fractions and Ksvand fa values are calculated.The results show that iodide has no clear quench-ing effects on all γ-crystallins,the quenching effects of acrylamide on the tryp-tophan fluorescences of γ1-γ2-and γ3-crystallin from lenses of the ...
基金This work was partly supported by the National "863 Projects" (2001AA320304).
文摘The pore formation mechanism of β-crystalline polypropylene under stretching was investigated. The porosity of the samples increases rapidly with stretching, having a maximum at draw ratios around 2 and then decreases monotonically. An abrupt formation process of initial micropores at very low draw ratios was evidenced by in situ SAXS measurements. At the same time the phase transition from β-crystal to α-crystal proceeds slowly in the whole deformation process up to large draw ratios around 5. Comparative studies of α-and β-crystalline polypropylene samples before stretching indicate that in addition to difference in crystal forms the α-and β-crystalline polypropylene samples exhibit quite different morphological features. There are a lot of interfaces in β-crystalline polypropylene samples, which may have a lower density value and can be easily etched by argon ions and penetrated by small molecules. It was concluded from these experimental facts that the pore formation and crystal transition are two independent phenomena during the deformation of β-crystalline polypropylene samples, and phase transition from β-crystal to α-crystal could hardly be the origin of pore formation. A defect initiation mechanism was proposed to understand the pore formation behavior of β-crystalline polypropylenes.
文摘Differential scanning calorimetry and X-ray diffraction experiments on β-nucleated polypropylene were made on the samples crystallized at different temperatures and processed by injection molding. The crystal perfection was shown to vary with crystallization temperature. The observed multiple peaks could be related to a ill-phase with defective inclination of the chains, a recrystallized or original β_2-phase of more perfect inclination, and the α-phase. Injection molded samples could be analyzed from the established DSC interpretation.
文摘a-Crystallin is the major structural protein of eye lens of vertebrates. In human lens, the ratio of aA-crystallin to aB-crystallin was found to be 3:1. aA-Crystallin contains two cysteine residues at positions 131 and 142, which are at the junction between the a-crystallin domain and the C-terminal tail. We used the accessibility of the thiol groups by Ellman’s reagent (DTNB) as a tool to gain information about the various structural perturbations of hinge region of a-crystallin and during the binding with substrates. In the native condition, the cys-142 though reacted quite fast was not fully exposed. Several reagents were used to see the accessibility of cys-131. Rate constant for cys-131 was increased gradually with increase in the concentration of reagents. The bindings of substrates are affected by the accessibility of thiol indicating that the substrates bind to the hinge region of a-crystallin. By blocking of cys-142, it was observed that the accessibility of one thiol depends on the other thiol, and they are not independent. The hinge region of a-crystallin is very important as substrate binding site and from this study we have got various structural information about that region.
