An improved clean sonoreactor-based method for protein identification by mass spectrometry-based techniques

A new clean fast (8 min) method for in-solution protein digestion without detergent or urea for protein identification by peptide mass fingerprint and mass spectrometry-based techniques is proposed. The new method avoids the use of time consuming desalting procedures entailing the following four steps done under the effect of an ultrasonic field provided by a sonoreactor: denaturation (1 min) in a mixed solution of water:acetonitrile 1/1 (v/v); protein reduction (1 min); protein alkylation (1 min); and protein digestion (5 min). Five proteins with masses comprised between 14.4 kDa and 97 kDa and the protein split-soret cytochrome c from D. desulfuricans ATCC27774, were successfully identified with this procedure. No differences were found in the sequence coverage or in the number of peptides matched when the new clean method was compared to another one using urea. Twofold better signal-to-noise ratios were obtained in the MALDI spectra from protein samples prepared with the new method when comparing it with a method using urea. The new digestion method avoids the need to remove salt content and increases throughput (six samples at once) while reducing sample loss and contamination from sample handling.     

Micro-Raman analysis of coloured lithographs

Raman micro-spectroscopy was chosen for analysis and identification of the pigments present in four nineteenth-century hand-coloured lithographs, as this technique has several advantages over others for this purpose. The possibility of performing completely non-destructive analysis without any sampling is probably one of its most favourable qualities for art analysis. Raman spectroscopy can also be used to determine some pigments that cannot be detected using FTIR, such as vermilion, carbon blacks, cadmium pigments, etc. Among others, Prussian blue, ultramarine blue, carbon black, chrome yellow, yellow ochre, red lead, red iron oxide, burnt Sienna, indigo blue, chrome orange, phthalocyanine green, and some other organic pigments, were determined in the specimens. The results obtained have led to doubts about the age of the lithographs.     

Identification and discrimination of Pseudomonas aeruginosa bacteria grown in blood and bile by laser-induced breakdown spectroscopy

Pseudomonas aeruginosa bacteria colonies have been analyzed by laser-induced breakdown spectroscopy using nanosecond laser pulses. LIBS spectra were obtained after transferring the bacteria from a nutrient-rich culture medium to a nutrient-free agar plate for laser ablation. To study the dependence of the LIBS spectrum on growth and environmental conditions, colonies were cultured on three different nutrient media: a trypticase soy agar (TSA) plate, a blood agar plate, and a medium chosen deliberately to induce bacteria membrane changes, a MacConkey agar plate containing bile salts. Nineteen atomic and ionic emission lines in the LIBS spectrum, which was dominated by inorganic elements such as calcium, magnesium and sodium, were used to identify and classify the bacteria. A discriminant function analysis was used to discriminate between the P. aeruginosa bacteria and two strains of E. coli: a non-pathogenic environmental strain and the pathogenic strain enterohemorrhagic E. coli 0157:H7 (EHEC). Nearly identical spectra were obtained from P. aeruginosa grown on the TSA plate and the blood agar plate, while the bacteria grown on the MacConkey plate exhibited easily distinguishable differences from the other two. All P. aeruginosa samples, independent of initial growth conditions, were readily discriminated from the two E. coli strains.     

Purification and Structure Identification of Hyaluronic Acid

Polysaccharide produced by mutated strain of Streptococcus zooepidemicus was purified by the procedures including Savage method, quaternary ammonium compound precipitation, DEAE-cellulose(DE52) chromatography and Sephadex G-75 gel filtration. The structure of the purified polysaccharide has been characterized by means of chemical composition analysis,13C NMR spectrum, infrared spectrum and circular dichroism (CD). All the results showed that the purified polysaccharide was hyaluronic acid (HA). The single helix conformation of the purified HA was determined by Congo red experiment. The molecular weight of the HA was about 1.16×106D, which was measured by viscosity method.     

南海黄蜂海绵中系列长链甲基酮成分分析

从中国南海海绵Spheciospongia Vagabunda乙酸乙酯萃取部分中分离出一组混合物,应用^13HNMR,^13CNMR,H-HCOSY和GC／MS等光谱分析技术对它们的结构进行了分析,主要为一些长链甲基酮化合物。共鉴定出二十四碳烯-2-酮异构体、二十四碳二烯-2-酮和二十四碳烯-2-酮等14种化合物,其中4种化合物的双键位置有待于进一步确定。     

Evaluation of novel sample identification approach based on chromatographic fingerprint set correlation homogeneity analysis

Instead of usual rationale for chromatographic fingerprint based sample identification which relies upon visual inspection or principal component analysis of raw or aligned chromatograms novel nonparametric statistical measure of fingerprint set homogeneity is proposed. Randomization test is applied for significance analysis of fingerprint set homogeneity while average maximum crosscorrelation is used as a merit function. Chromatogram sets generated by random selection from standard and unknown sample chromatogram collections are compared with respect to merit function values with set of chromatograms that represents standard and/or unknown sample. In that instance fingerprint homogeneity significance is represented by the fraction of random chromatogram sets that have higher merit values than the standard and/or unknown sample sets. A set of peptide maps corresponding to different haemoglobin variants has been selected for evaluation of proposed test. This approach is compared to chromatogram alignment based on correlation optimized warping coupled with principal component or cluster analysis. Proposed method is simple i.e. straightforward sample identification procedure which reliability has been evaluated here. Impact of this approach on peptide mapping validation and system suitability analysis is discussed.     

UKF在惯导平台误差系数辨识离心机测试中的应用

针对惯导平台误差系数辨识的离心机测试,利用直接法建立了误差系数辨识的非线性模型,并结合实际系统模型的特点对标准UKF算法进行了简化和改进.改进后的UKF结构简单,与标准UKF具有同样的滤波精度,并且减小了计算量,提高了计算效率.然后利用扩展Kalman滤波(EKF)算法和改进的UKF算法对惯导平台误差系数辨识离心机测试进行仿真.结果表明,与EKF算法相比,改进的UKF算法能提高惯导平台误差系数的辨识精度,并且更容易实现.