The aim of this study was to purify and characterize a keratinase produced by a new isolated Bacillus subtilis KD-N2 strain. The keratinase produced by the isolate was purified using ammonium sulphate precipitation, S...The aim of this study was to purify and characterize a keratinase produced by a new isolated Bacillus subtilis KD-N2 strain. The keratinase produced by the isolate was purified using ammonium sulphate precipitation, Sephadex G-75 and DEAE (diethylaminoethyl)-Sepharose chromatographic techniques. The purified enzyme was shown to have a molecular mass of 30.5 kDa, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The optimum pH at 50 °C was 8.5 and the optimum temperature at pH 8.5 was 55 °C. The keratinase was partially inactivated by some metal ions, organic solvents and serine protease inhibitor phenylmethanesulfonyl fluoride (PMSF). Sodium dodecyl sulfate (SDS) and ethylene diamine tetraacetic acid (EDTA) had positive effect on the keratinase activity. Reducing agents including dithiothreitol (DTT), mercaptoethanol, L-cysteine, sodium sulphite, as well as chemicals of SDS, ammonium sulfamate and dimethylsulfoxide (DMSO) stimulated the enzyme activity upon a feather meal substrate. Besides feather keratin, the enzyme is active upon the soluble proteins ovalbumin, bovine serum albumin (BSA), casein and insoluble ones as sheep wool and human hair. Calf hair, silk and collagen could not be hydrolyzed by the keratinase.展开更多
不宁腿综合征（Restless legs syndrome）是一种常见的中枢神经系统疾病，分为原发性和继发性，是指睡眠间期发生非痛性、非痉挛性腿部不适，需经过频繁腿部移动才能缓解。正常人群不宁腿综合征的发病率为5％，并且多为原发性，继发性...不宁腿综合征（Restless legs syndrome）是一种常见的中枢神经系统疾病，分为原发性和继发性，是指睡眠间期发生非痛性、非痉挛性腿部不适，需经过频繁腿部移动才能缓解。正常人群不宁腿综合征的发病率为5％，并且多为原发性，继发性不宁腿综合征多见于慢性肾功能不全、糖尿病等疾病的慢性并发症”。尿毒症血液透析患者不宁腿综合征发病率高达20％-40％，常伴有运动神经传导速度减慢和肌震颤，多数患者肾移植后症状缓解。展开更多
To purify and identify the simian parvovirus （SPV） protein Vp2 expressed in E. coli, fusion protein of SPV Vp2 was expressed in E. coli DHSα competent cells transformed with vector pThioHis AVp2, and the new bacter...To purify and identify the simian parvovirus （SPV） protein Vp2 expressed in E. coli, fusion protein of SPV Vp2 was expressed in E. coli DHSα competent cells transformed with vector pThioHis AVp2, and the new bacterial protein extraction reagent was used to extract the protein. Detergents with different characteristics were used to solubilize the fusion protein, and metal chelating resin （ProBond） with a continuous elusion polyacrylamide gel electrophoresis procedure was employed to purify the fusion protein. SDS-PAGE gel stained with coomassie blue and Western-blotting probed with anti-thio and anti-SPV Vp2 antibodies were used to identify the specificity of the expressed and purified fusion proteins. It was found that the SPV Vp2 protein expressed in E. coli was highly insoluble, and could not be solublized by the commonly used detergent. However, 6 M urea could solubilize the fusion proteins and was then employed for the further purification procedure, but metal chelating resin could not be used for this procedure, because of the loss of the tertiary structure of HP-thiaoredoxin and the metal-binding domain. The technique with continuous elusion polyacrylamide gel electrophoresis yielded a homogenous protein with a single band on the gel stained with coomassie blue and retained reactivity with anti-thio or anti-SPV Vp2 antibodies. It is evident that this technique with successful purification of SPV Vp2 protein has practical significance for the further investigation on the simian parvovirus infection.展开更多
We propose a scheme to purify entanglement of two atoms from not-too-impure entangled states by checking the parity of the two atoms through the cavity input-output process. As the parity check is made by measurement ...We propose a scheme to purify entanglement of two atoms from not-too-impure entangled states by checking the parity of the two atoms through the cavity input-output process. As the parity check is made by measurement on single-photon polarization, which would not affect the entanglement of the two atoms, our scheme has the successful probability double of that in a previous well-known scheme with linear optical elements [Nature （London） 410 （2001） 1067], and is insensitive to the photon loss and the detection inefficieney. Experimental feasibility of our scheme with current technology is discussed.展开更多
文摘The aim of this study was to purify and characterize a keratinase produced by a new isolated Bacillus subtilis KD-N2 strain. The keratinase produced by the isolate was purified using ammonium sulphate precipitation, Sephadex G-75 and DEAE (diethylaminoethyl)-Sepharose chromatographic techniques. The purified enzyme was shown to have a molecular mass of 30.5 kDa, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The optimum pH at 50 °C was 8.5 and the optimum temperature at pH 8.5 was 55 °C. The keratinase was partially inactivated by some metal ions, organic solvents and serine protease inhibitor phenylmethanesulfonyl fluoride (PMSF). Sodium dodecyl sulfate (SDS) and ethylene diamine tetraacetic acid (EDTA) had positive effect on the keratinase activity. Reducing agents including dithiothreitol (DTT), mercaptoethanol, L-cysteine, sodium sulphite, as well as chemicals of SDS, ammonium sulfamate and dimethylsulfoxide (DMSO) stimulated the enzyme activity upon a feather meal substrate. Besides feather keratin, the enzyme is active upon the soluble proteins ovalbumin, bovine serum albumin (BSA), casein and insoluble ones as sheep wool and human hair. Calf hair, silk and collagen could not be hydrolyzed by the keratinase.
文摘不宁腿综合征（Restless legs syndrome）是一种常见的中枢神经系统疾病，分为原发性和继发性，是指睡眠间期发生非痛性、非痉挛性腿部不适，需经过频繁腿部移动才能缓解。正常人群不宁腿综合征的发病率为5％，并且多为原发性，继发性不宁腿综合征多见于慢性肾功能不全、糖尿病等疾病的慢性并发症”。尿毒症血液透析患者不宁腿综合征发病率高达20％-40％，常伴有运动神经传导速度减慢和肌震颤，多数患者肾移植后症状缓解。
文摘To purify and identify the simian parvovirus （SPV） protein Vp2 expressed in E. coli, fusion protein of SPV Vp2 was expressed in E. coli DHSα competent cells transformed with vector pThioHis AVp2, and the new bacterial protein extraction reagent was used to extract the protein. Detergents with different characteristics were used to solubilize the fusion protein, and metal chelating resin （ProBond） with a continuous elusion polyacrylamide gel electrophoresis procedure was employed to purify the fusion protein. SDS-PAGE gel stained with coomassie blue and Western-blotting probed with anti-thio and anti-SPV Vp2 antibodies were used to identify the specificity of the expressed and purified fusion proteins. It was found that the SPV Vp2 protein expressed in E. coli was highly insoluble, and could not be solublized by the commonly used detergent. However, 6 M urea could solubilize the fusion proteins and was then employed for the further purification procedure, but metal chelating resin could not be used for this procedure, because of the loss of the tertiary structure of HP-thiaoredoxin and the metal-binding domain. The technique with continuous elusion polyacrylamide gel electrophoresis yielded a homogenous protein with a single band on the gel stained with coomassie blue and retained reactivity with anti-thio or anti-SPV Vp2 antibodies. It is evident that this technique with successful purification of SPV Vp2 protein has practical significance for the further investigation on the simian parvovirus infection.
基金supported by National Natural Science Foundation of China under Grant Nos.10774163,10774042,and 10747167the State Key Basic Research Program of China under Grant Nos.2005CB724502 and 2006CB921203
文摘We propose a scheme to purify entanglement of two atoms from not-too-impure entangled states by checking the parity of the two atoms through the cavity input-output process. As the parity check is made by measurement on single-photon polarization, which would not affect the entanglement of the two atoms, our scheme has the successful probability double of that in a previous well-known scheme with linear optical elements [Nature （London） 410 （2001） 1067], and is insensitive to the photon loss and the detection inefficieney. Experimental feasibility of our scheme with current technology is discussed.
