The murine peptidylarginine deiminase (PAD) has five isoforms encoded by different genes and participates in a variety of cellular functions through the citrullination of target proteins. The crystal structure of huma...The murine peptidylarginine deiminase (PAD) has five isoforms encoded by different genes and participates in a variety of cellular functions through the citrullination of target proteins. The crystal structure of human PAD4 with a dimeric form was previously solved because of the enzyme’s relevance to rheumatoid arthritis. PAD6, abundant in mouse oocytes and eggs, is believed to take part in early events of embryogenesis, but its biochemical properties are little understood. Here we have purified and characterized a recombinant PAD6. A PAD6 cDNA was cloned from mouse ovary RNA and expressed in Escherichia coli through pET29 and pGEX vectors. When benzoyl-L-arginine ethyl ester was used as a substrate, no appreciable activity was detected with a cell homogenate under conditions where a human PAD4 cDNA caused significant activity. Both proteins were affinity-purified to near homogeneity. The circular dichroism spectra of PAD6 and human PAD4 were similar in the far ultraviolet region. On molecular sieving, PAD6 was eluted faster than human PAD4. The cross-linking of PAD6 with dimethyl suberimidate clearly showed six bands on an sodium dodecyl sulfate-polyacrylamide gel. These results indicate that PAD6 can constitute a hexameric structure. The purified PAD6 still showed no enzymatic activity. This unique structure and loss in enzymatic activity is strongly suggested to favor the formation of egg cytoplasmic sheets as the architectural protein.展开更多
Cryo-electron microscopy(cryo-EM) provides a powerful tool to resolve the structure of biological macromolecules in natural state. One advantage of cryo-EM technology is that different conformation states of a protein...Cryo-electron microscopy(cryo-EM) provides a powerful tool to resolve the structure of biological macromolecules in natural state. One advantage of cryo-EM technology is that different conformation states of a protein complex structure can be simultaneously built, and the distribution of different states can be measured. This provides a tool to push cryo-EM technology beyond just to resolve protein structures, but to obtain the thermodynamic properties of protein machines. Here, we used a deep manifold learning framework to get the conformational landscape of Kai C proteins, and further obtained the thermodynamic properties of this central oscillator component in the circadian clock by means of statistical physics.展开更多
为了降低天然大分子功能蛋白的分离纯化成本,以琼脂为原料自制弱阴离子交换层析介质DEAE-琼脂凝胶微球。将DEAE-琼脂凝胶微球应用于坛紫菜R-藻红蛋白（R-PE）和螺旋藻C-藻蓝蛋白（C-PC）的提取分离,最佳洗脱条件为：层析柱规格h=35.0 cm...为了降低天然大分子功能蛋白的分离纯化成本,以琼脂为原料自制弱阴离子交换层析介质DEAE-琼脂凝胶微球。将DEAE-琼脂凝胶微球应用于坛紫菜R-藻红蛋白（R-PE）和螺旋藻C-藻蓝蛋白（C-PC）的提取分离,最佳洗脱条件为：层析柱规格h=35.0 cm,φ=1.0 cm,V=27.5 m L;流速v=0.33 m L/min;洗脱缓冲液为0.01 mol/L磷酸盐溶液（含有0.05~0.5 mol/L Na Cl溶液）;0.01 mol/L磷酸盐缓冲液（含0.1 mol/L Na Cl）洗脱出纯度为5.0的坛紫菜R-PE;0.01 mol/L磷酸盐缓冲液（含0.2 mol/L Na Cl）洗脱出纯度为4.4的螺旋藻C-PC。自制层析介质成本低廉、耗能少、可大量制备、分离效果好,可用于坛紫菜R-PE、螺旋藻C-PC的产业化制备。展开更多
The parent aniline hexamer was synthesized in the emeraldine base(EB) oxidation state through one step oxidative coupling reaction using parent aniline trimer in the leucoemeraldine oxidation state. The hexamer in the...The parent aniline hexamer was synthesized in the emeraldine base(EB) oxidation state through one step oxidative coupling reaction using parent aniline trimer in the leucoemeraldine oxidation state. The hexamer in the EB state was reduced by phenylhydrazine in ethanol and was characterized by IR, 1H NMR , MALDI TOF MS and elemental analysis. The chemical oxidation process of the hexamer was studied by UV Vis spectra. It was found that the hexamer was oxidized to its EB form and then to the pernigraniline oxidation state.展开更多
文摘The murine peptidylarginine deiminase (PAD) has five isoforms encoded by different genes and participates in a variety of cellular functions through the citrullination of target proteins. The crystal structure of human PAD4 with a dimeric form was previously solved because of the enzyme’s relevance to rheumatoid arthritis. PAD6, abundant in mouse oocytes and eggs, is believed to take part in early events of embryogenesis, but its biochemical properties are little understood. Here we have purified and characterized a recombinant PAD6. A PAD6 cDNA was cloned from mouse ovary RNA and expressed in Escherichia coli through pET29 and pGEX vectors. When benzoyl-L-arginine ethyl ester was used as a substrate, no appreciable activity was detected with a cell homogenate under conditions where a human PAD4 cDNA caused significant activity. Both proteins were affinity-purified to near homogeneity. The circular dichroism spectra of PAD6 and human PAD4 were similar in the far ultraviolet region. On molecular sieving, PAD6 was eluted faster than human PAD4. The cross-linking of PAD6 with dimethyl suberimidate clearly showed six bands on an sodium dodecyl sulfate-polyacrylamide gel. These results indicate that PAD6 can constitute a hexameric structure. The purified PAD6 still showed no enzymatic activity. This unique structure and loss in enzymatic activity is strongly suggested to favor the formation of egg cytoplasmic sheets as the architectural protein.
基金supported by the National Natural Science Foundation of China (Grant No. 12090054)。
文摘Cryo-electron microscopy(cryo-EM) provides a powerful tool to resolve the structure of biological macromolecules in natural state. One advantage of cryo-EM technology is that different conformation states of a protein complex structure can be simultaneously built, and the distribution of different states can be measured. This provides a tool to push cryo-EM technology beyond just to resolve protein structures, but to obtain the thermodynamic properties of protein machines. Here, we used a deep manifold learning framework to get the conformational landscape of Kai C proteins, and further obtained the thermodynamic properties of this central oscillator component in the circadian clock by means of statistical physics.
文摘为了降低天然大分子功能蛋白的分离纯化成本,以琼脂为原料自制弱阴离子交换层析介质DEAE-琼脂凝胶微球。将DEAE-琼脂凝胶微球应用于坛紫菜R-藻红蛋白（R-PE）和螺旋藻C-藻蓝蛋白（C-PC）的提取分离,最佳洗脱条件为：层析柱规格h=35.0 cm,φ=1.0 cm,V=27.5 m L;流速v=0.33 m L/min;洗脱缓冲液为0.01 mol/L磷酸盐溶液（含有0.05~0.5 mol/L Na Cl溶液）;0.01 mol/L磷酸盐缓冲液（含0.1 mol/L Na Cl）洗脱出纯度为5.0的坛紫菜R-PE;0.01 mol/L磷酸盐缓冲液（含0.2 mol/L Na Cl）洗脱出纯度为4.4的螺旋藻C-PC。自制层析介质成本低廉、耗能少、可大量制备、分离效果好,可用于坛紫菜R-PE、螺旋藻C-PC的产业化制备。
文摘The parent aniline hexamer was synthesized in the emeraldine base(EB) oxidation state through one step oxidative coupling reaction using parent aniline trimer in the leucoemeraldine oxidation state. The hexamer in the EB state was reduced by phenylhydrazine in ethanol and was characterized by IR, 1H NMR , MALDI TOF MS and elemental analysis. The chemical oxidation process of the hexamer was studied by UV Vis spectra. It was found that the hexamer was oxidized to its EB form and then to the pernigraniline oxidation state.
