We present here the first observation of cathodoluminescence (CL) images of Met.(Cu, Ag)-TCNQ anion radical salts organic thin films which were prepared in sat urated TCNQ/CH3CN liquid-phase by self-growth. The erperi...We present here the first observation of cathodoluminescence (CL) images of Met.(Cu, Ag)-TCNQ anion radical salts organic thin films which were prepared in sat urated TCNQ/CH3CN liquid-phase by self-growth. The erperiments were carried out by means of Hitachi S-450 type scanning electron microscopy(SEM). Comparsion of CL images with secondary electron(SE) images of the same point on the organic thin film indicates that the shape of Met.(Cu, Ag)-TCNQ in CL images corresponds very well to that in the SE images. The results observed also shows that the CL intensity of CuTCNQ is stronger than that of AgTCNQ under the same experimental conditions. Based on the above results, a brief discussion about the preliminary mechanism of CL from Met.(Cu,Ag)-TCNQ has been given.展开更多
In order to obtain phase information for the X-ray diffraction of tabtoxin resistance protein (TTR) crystal using the MAD phasing method, a selenomethionine (Se-Met) derivative of TTR was overexpressed in E. coli stra...In order to obtain phase information for the X-ray diffraction of tabtoxin resistance protein (TTR) crystal using the MAD phasing method, a selenomethionine (Se-Met) derivative of TTR was overexpressed in E. coli strain M15, with pQE-30 plasmid, through IPTG induction in M9 medium containing Se-Met. The product was purified to an estimated homogeneity of greater than 95% according to SDS-PAGE, by a Ni-NTA metal affinity followed by a Mono Q anion exchange column chromatography. The successful substitution of Se-Met for methionine (Met) was confirmed by MALDI-TOF and ESI-Quadrupole Mass Spectrometry analysis. The derivative crystal was obtained using similar conditions as those for the native.展开更多
The cephalosporin acylases are a group of enzymes that hydrolyze cephalosporin C and/or glutaryl 7 aminocephalosporanic acid to produce 7 aminocephalosporanic acid. The cephalosporin acylase from Pseudomonas sp. ...The cephalosporin acylases are a group of enzymes that hydrolyze cephalosporin C and/or glutaryl 7 aminocephalosporanic acid to produce 7 aminocephalosporanic acid. The cephalosporin acylase from Pseudomonas sp. strain 130 was crystallized in two different forms suitable for structural studies. A tetragonal crystal form diffracted to 0.24 nm belonged to the space group P4 12 12. There was one αβ heterodimer per asymmetric unit. A second crystal form diffracted to 0.21 nm belonged to the space group P2 1. There was four αβ heterodimers per asymmetric unit. The tetragonal crystal structure of CA 130 was determined using the multiwavelength anomalous diffraction method and the P2 1 crystal structure was then determined using the molecular replacement method.展开更多
文摘We present here the first observation of cathodoluminescence (CL) images of Met.(Cu, Ag)-TCNQ anion radical salts organic thin films which were prepared in sat urated TCNQ/CH3CN liquid-phase by self-growth. The erperiments were carried out by means of Hitachi S-450 type scanning electron microscopy(SEM). Comparsion of CL images with secondary electron(SE) images of the same point on the organic thin film indicates that the shape of Met.(Cu, Ag)-TCNQ in CL images corresponds very well to that in the SE images. The results observed also shows that the CL intensity of CuTCNQ is stronger than that of AgTCNQ under the same experimental conditions. Based on the above results, a brief discussion about the preliminary mechanism of CL from Met.(Cu,Ag)-TCNQ has been given.
基金This work wassupported by the National Natural Science Foundation of China (Grant Nos. 39870174 and 39970155) the National "863" Project (Grant No. 103130306) and the National "973" Project (Grant Nos. G1999075602, G19990II902 and 1998051105).
文摘In order to obtain phase information for the X-ray diffraction of tabtoxin resistance protein (TTR) crystal using the MAD phasing method, a selenomethionine (Se-Met) derivative of TTR was overexpressed in E. coli strain M15, with pQE-30 plasmid, through IPTG induction in M9 medium containing Se-Met. The product was purified to an estimated homogeneity of greater than 95% according to SDS-PAGE, by a Ni-NTA metal affinity followed by a Mono Q anion exchange column chromatography. The successful substitution of Se-Met for methionine (Met) was confirmed by MALDI-TOF and ESI-Quadrupole Mass Spectrometry analysis. The derivative crystal was obtained using similar conditions as those for the native.
基金Supported by the National Natural Science Foundation (No. 39970 15 5 ) the High- Technology Developm entProgram of China (No. 2 0 0 1AA2 330 11) +1 种基金and theNational Frontier Research Program (No.G19990 75 6 0 2 G19990 1190 2 and19980 5 110 5 )
文摘The cephalosporin acylases are a group of enzymes that hydrolyze cephalosporin C and/or glutaryl 7 aminocephalosporanic acid to produce 7 aminocephalosporanic acid. The cephalosporin acylase from Pseudomonas sp. strain 130 was crystallized in two different forms suitable for structural studies. A tetragonal crystal form diffracted to 0.24 nm belonged to the space group P4 12 12. There was one αβ heterodimer per asymmetric unit. A second crystal form diffracted to 0.21 nm belonged to the space group P2 1. There was four αβ heterodimers per asymmetric unit. The tetragonal crystal structure of CA 130 was determined using the multiwavelength anomalous diffraction method and the P2 1 crystal structure was then determined using the molecular replacement method.
