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  • Two-dimensional polyacrylamide gel electrophoresis  (7)
  • Analytical Chemistry and Spectroscopy  (2)
  • 1995-1999  (9)
  • 1998  (9)
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  • 1995-1999  (9)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Fluorescence and surface-enhanced Raman study of 9-aminoacridine in relation to its aggregation and excimer emission in aqueous solution and on silver surface (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 327-339 
    Details
    ISSN: 1075-4261
    Keywords: 9-aminoacridine ; fluorescence ; SERS ; dimerization ; excimer ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Fluorescence spectroscopy and surface-enhanced Raman spectroscopy (SERS) have been applied to study the aggregation and excimer emission of 9-aminoacridine (9AA) and 9-aminoacridine hydrochloride (9AA-HCl) in aqueous solution and on silver colloids. The effect of the drug concentration, pH, and chloride concentration on these processes has been investigated. The excimer emission of 9AA is connected to the dimerization of this drug in solution: the formation of 9AA dimers is greatly favored when the drug is under the amino form at neutral and acidic pH, while at alkaline pH the imino 9AA form tends to form large-sized aggregates which cannot be excited to render excimer emission. 9AA is adsorbed on the silver surface under two different forms: strongly and weakly attached 9AA, each one corresponding to the different drug tautomers: imino and amino. The interaction of 9AA with silver induces a charge transfer from the adsorbate to the metal leading to a remarkable fluorescence quenching, a basicity decrease of the adsorbed drug and a considerable weakening of the dimer-excimer emission. Furthermore, an attribution of the main Raman features appearing in the SERS spectra has been proposed, providing marker bands for the imino and amino 9AA tautomers, and a mechanism for the molecular dimerization is also suggested. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 327-339, 1998
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    2,3-Di-O-pentyl-6-O-tert-butyldimethylsilyl-β-cyclodextrin as a Chiral Stationary Phase in Capillary Gas Chromatography (1998)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 225-233 
    Details
    ISSN: 0935-6304
    Keywords: Chiral GC ; chiral stationary phase ; cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---2,3-Di-O-pentyl-6-O-tert-butyldimethylsilyl-β-cyclodextrin has been evaluated as an enantioselective stationary phase for capillary gas chromatography. Experimental results show a good enantioselectivity towards compounds with different functional groups (haloalkanes, alcohols, esters, terpenoids, amino acid derivatives, and heterocycles). Column stability improves mixing the chiral phase with polysiloxane SE-54 (1 : 1).
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Extraction of membrane proteins by differential solubilization for separation using two-dimensional gel electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 837-844 
    Details
    ISSN: 0173-0835
    Keywords: Membrane proteins ; Solubility ; Two-dimensional polyacrylamide gel electrophoresis ; Proteome ; Escherichia coli ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We describe the extraction and enrichment of membrane proteins for separation by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) after differential solubilization of an Escherichia coli cell lysate. In a simple three-step sequential solubilization protocol applicable for whole cell lysates, membrane proteins are partitioned from other cellular proteins by their insolubility in solutions conventionally used for isoelectric focusing (IEF). As the first step, Tris-base was used to solubilize many cytosolic proteins. The resultant pellet was then subjected to conventional solubilizing solutions (urea, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, dithiothreitol, Tris, carrier ampholytes). Following the completion of this step, 89% of the initial E. coli sample mass was solubilized. Finally, the membrane protein rich pellet was partially solubilized using a combination of urea, thiourea, tributyl phosphine and multiple zwitterionic surfactants. Using N-terminal sequence tagging and peptide mass fingerprinting we have identified 11 membrane proteins from this pellet. Two of these outer membrane proteins (Omp), OmpW and OmpX, have previously been known only as an open reading frame in E. coli, while OmpC, OmpT and OmpTOLC have not previously been identified on a 2-D gel. The prefractionation of an entire cell lysate into multiple fractions, based on solubility, results in simplified protein patterns following 2-D PAGE using broad-range pH 3.5-10 immobilized pH gradients (IPGs). Additional advantages of sample prefractionation are that protein identification and gel matching, for database construction, is a more manageable task, the procedure requires no specialized apparatus, and the sequential extraction is conducted in a single centrifuge tube, minimizing protein loss.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190539
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  • 4
    Electronic Resource
    Electronic Resource
    Analyzing glycoproteins separated by two-dimensional gel electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 981-988 
    Details
    ISSN: 0173-0835
    Keywords: Glycoprotein ; Two-dimensional polyacrylamide gel electrophoresis ; α1-Antitrypsin ; α2-HS Glycoprotein ; Protein isoforms ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional (2-D) electrophoresis is the preferred method for separating the glycoforms of proteins. The isoforms usually present as ‘trains’ of spots in the first dimension and may also differ in molecular weight. The primary goal for analyzing the carbohydrate content of glycoprotein spots is to understand the ‘rules’ which govern the migration of glycoproteins in 2-D electrophoresis. These rules can then be used to produce predictive vectors to interpret changes in glycosylation patterns. Techniques for the analysis of oligosaccharides released from glycoproteins which have been electroblotted to PVDF membrane after one-dimensional (1-D) and 2-D preparative gel electrophoresis are described. The oligosaccharides are removed enzymatically (PNGase F of N-linked oligosaccharides) or chemically (β-elimination of O-linked oligosaccharides) and separated by high performance anion exchange chromatography (HPAEC-PAD) and identified by electrospray ionization mass spectrometry (ESI-MS) or analyzed directly by ESI-MS. After enzymic removal of the N-linked oligosaccharides the protein spots can be further analyzed by Edman sequence tagging for identification and quantitation of the protein and by acid hydrolysis for monosaccharide analysis of the O-linked oligosaccharides. These approaches have been proved on 1-D PAGE electroblotted bovine fetuin and human glycophorin A and then used to analyze two abundant proteins which separate as glycoforms on 2-D PAGE preparative narrow range (pH 4.5-5.5) blots of human plasma: α2-HS glycoprotein (human fetuin) and α1-antitrypsin (α1-protease inhibitor). It is apparent that both the macroheterogeneity (site occupation) and microheterogeneity (diversity of structures) of the glycosylation contribute to the separation of protein isoforms in 2-D PAGE.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190613
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  • 5
    Electronic Resource
    Electronic Resource
    Towards an automated approach for protein identification in proteome projects (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1941-1949 
    Details
    ISSN: 0173-0835
    Keywords: Proteome ; Automation ; Two-dimensional polyacrylamide gel electrophoresis ; Mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The development of automated, high throughput technologies for the rapid identification of proteins is essential for large-scale proteome projects. While a degree of automation already exists in some stages of the protein identification process, such as automated acquisition of matrix assisted laser desorption ionisation  -  time of flight (MALDI-TOF) mass spectra, efficient interfaces between different stages are still lacking. We report the development of a highly automated, integrated system for large scale identification of proteins separated by two-dimensional gel electrophoresis (2-DE), based on peptide mass fingerprinting. A prototype robotic system was used to image and excise 288 protein spots from an amido black stained polyvinylidene difluoride (PVDF) blot. Protein samples were enzymatically digested with a commercial automated liquid handling system. MALDI-TOF mass spectrometry was used to acquire mass spectra automatically, and the data analysed with novel automated peptide mass fingerprinting database interrogation software. Using this highly automated system, we were able to identify 95 proteins on the basis of peptide mass fingerprinting, isoelectric point and molecular weight, in a period of less than ten working days. Advantages, problems, and future developments in robotic excision systems, liquid handling, and automated database interrogation software are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191112
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  • 6
    Electronic Resource
    Electronic Resource
    Two-dimensional gel electrophoresis for proteome projects: The effects of protein hydrophobicity and copy number (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1501-1505 
    Details
    ISSN: 0173-0835
    Keywords: Proteome ; Two-dimensional polyacrylamide gel electrophoresis ; Protein hydrophobicity ; Protein copy number ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional (2-D) gel electrophoresis is often used in proteome projects to provide a global view of the proteins expressed in any cell or tissue type. Here we have investigated the effects of protein hydrophobicity and cellular protein copy number on a protein's presence or absence on a two-dimensional gel. The average hydropathy values of all known proteins from Bacillus subtilis, Escherichia coli and Saccharomyces cerevisiae were calculated, thus defining the range of protein hydrophobicity and hydrophilicity in these organisms. The average hydropathy values were then calculated for a total of 427 proteins from these species, which had been identified elsewhere on 2-D gels. Strikingly, it was seen that no highly hydrophobic proteins, as defined by average hydrophobicity values, have been found to date on 2-D gel separations of whole cell lysates. A clear hydrophobicity cutoff point was seen, above which current 2-D electrophoresis methods appear not to be useful for protein separation. The effect of cellular protein copy number on a protein's presence on a 2-D gel was investigated by means of a graphical model. This model showed how variations in protein loading and copy number per cell interact to determine the quantity of a protein that will be present on a 2-D gel. Considering the current maximum in 2-D gel loading capacity, it was found that 2-D probably can not visualize or produce analytical quantities of proteins present at less than 1000 copies per cell. We conclude that further developments of 2-D electrophoresis techniques are desirable to enable the visualization and analysis of all proteins expressed by a cell or tissue.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190847
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  • 7
    Electronic Resource
    Electronic Resource
    A two-dimensional electrophoretic study of serum amyloid A and C-reactive protein in infants and children (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 776-781 
    Details
    ISSN: 0173-0835
    Keywords: C-reactive protein ; Paediatrics ; Serum amyloid A protein ; Two-dimensional polyacrylamide gel electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was used to analyze C-reactive - (CRP) and serum amyloid A protein (SAA) in infants and children. Five SAA isotypes were identified. CRP showed vertical streaking, and its optical density values correlated with immunoturbidimetric measurements. As evaluated by densitometry, both proteins showed an age-dependent variation. In more than 50% of the neonates, SAA was present in equal or higher amounts than CRP, and only SAA1α could be detected. In children, CRP was expressed in higher amounts than SAA, and both SAA1α and SAA2α were present. N-terminally modified forms of both isotypes were present regardless of age, including in premature infants. These results suggest that the overall synthesis of the gene products SAA1α and SAA2α is developmentally regulated, but at the same time that their N-terminal processing occurs independently of developmental factors. The presented data suggest that SAA has an important function in neonates, and that the role of SAA as an infection marker in this population should be investigated further.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190529
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  • 8
    Electronic Resource
    Electronic Resource
    '98 Escherichia coli SWISS-2DPAGE database update (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1960-1971 
    Details
    ISSN: 0173-0835
    Keywords: Two-dimensional polyacrylamide gel electrophoresis ; Escherichia coli ; SWISS-2DPAGE database ; Immobilized pH gradient ; Sequence tag ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The combination of two-dimensional polyacrylamide gel electrophoresis (2-DPAGE), computer image analysis and several protein identification techniques allowed the Escherichia coli SWISS-2DPAGE database to be established. This is part of the ExPASy molecular biology server accessible through the WWW at the URL address http://www.expasy.ch/ch2d/ch2d-top.html. Here we report recent progress in the development of the E. coli SWISS-2DPAGE database. Proteins were separated with immobilized pH gradients in the first dimension and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension. To increase the resolution of the separation and thus the number of identified proteins, a variety of wide and narrow range immobilized pH gradients were used in the first dimension. Micropreparative gels were electroblotted onto polyvinylidene difluoride membranes and spots were visualized by amido black staining. Protein identification techniques such as amino acid composition analysis, gel comparison and microsequencing were used, as well as a recently described Edman “sequence tag” approach. Some of the above identification techniques were coupled with database searching tools. Currently 231 polypeptides are identified on the E. coli SWISS-2DPAGE map: 64 have been identified by N-terminal microsequencing, 39 by amino acid composition, and 82 by sequence tag. Of 153 proteins putatively identified by gel comparison, 65 have been confirmed. Many proteins have been identified using more than one technique. Faster progress in the E. coli proteome project will now be possible with advances in biochemical methodology and with the completion of the entire E. coli genome.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191114
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  • 9
    Electronic Resource
    Electronic Resource
    Multiple parameter cross-species protein identification using MultiIdent - a world-wide web accessible tool (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 3199-3206 
    Details
    ISSN: 0173-0835
    Keywords: Protein identification ; Two-dimensional polyacrylamide gel electrophoresis ; Peptide mass fingerprinting ; Sequence tag ; Amino acid composition ; Proteomics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Recent increases in the number of genome sequencing projects means that the amount of protein sequence in databases is increasing at an astonishing pace. In proteome studies, this is facilitating the identification of proteins from molecularly well-defined organisms. However, in studies of proteins from the majority of organisms, proteins must be identified by comparing analytical data to sequences in databases from other species. This process is known as cross-species protein identification. Here we present a new program, MultiIdent, which uses multiple protein parameters such as amino acid composition, peptide masses, sequence tags, estimated protein pI and mass, to achieve cross-species protein identification. The program is structured so that protein amino acid composition, which is highly conserved across species boundaries, first generates a set of candidate proteins. These proteins are then queried with other protein parameters such as sequence tags and peptide masses. A final list of database entries which considers all analytical parameters is presented, ranked by an integrated score. We illustrate the power of the approach with the identification of a set of standard proteins, and the identification of proteins from dog heart separated by two-dimensional gel electrophoresis. The MultiIdent program is available on the world-wide web at: http://www.expasy.ch/sprot/multiident.html.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191824
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