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  • Analytical Chemistry and Spectroscopy  (7)
  • Biochemistry and Biotechnology  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Stabilization of λ repressor against thermal denaturation by site-directed Gly→Ala changes in α-helix 3 (1986)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 1 (1986), S. 43-46 
    Details
    ISSN: 0887-3585
    Keywords: protein stability ; helix-coil ; mutant ; calorimetry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Oligonucleotide-directed mutagenesis has been used to replace α-helical glycines in the N-terminal domain of λ repressor with alanines. Since alanine is a significantly better helix-forming residue than glycine, these changes were predicted to have a stabilizing effect. We show that the Gly46→Ala substitution, the Gly48→Ala substitution, and the double substitution increase the melting temperature of the N-terminal domain by 3-6°.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340010108
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  • 2
    Electronic Resource
    Electronic Resource
    Properdin factor B (Bf) distribution in North and Central American populations (1981)
    Weinheim : Wiley-Blackwell
    Electrophoresis 2 (1981), S. 320-323 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A study of properdin factor B (Bf) in 22 North and Central American populations demonstrated gene clusters delineating Old World Caucasian, New World and Black Ancestoral groups. Result of gene frequencies were comparable to data in the literature of European Caucasian and African Blacks. New World indigeneous population were clearly separated from other racial groups with hybrid population clustering in between the major genetic contributions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150020512
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of radioimmunoassay and gas chromatographic mass spectrometric assay for d-amphetamine (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1979), S. 187-190 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantification of low levels of psychotropic drugs (10-7 to 10-9 g ml-1) in small volumes of plasma requires sensitive and accurate methods. Validation of these methods is best achieved by comparing results obtained using several techniques. In this study, amphetamine levels in plasma were measured using gas chromatography mass spectrometry and radioimmunoassay. Correlation of the results obtained by the two methods was found to be positive and high (R = 0.9822). The average coefficient of variation between assays for gas chromatography mass spectrometry was 5.8% and for radioimmunoassay was 12.3%, while the average coefficient of variation within assays for gas chromatography mass spectrometry was 4.9% and for radioimmunoassay 6.9%. Although gas chromatography mass spectrometry was 1.9 times more sensitive than radioimmunoassay, for most purposes, the convenience of the radioimmunoassay method outweighs the technical superiority of gas chromatography mass spectrometry.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200060503
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  • 4
    Electronic Resource
    Electronic Resource
    Microelectrophoresis in the differential diagnosis of proteinuric diseasesThe authors would like to dedicate this publication to Professor Dr. med. F. Scheler, Head of the Department of Nephrology, University of Göttingen, on the occasion of his 60th birthday. (1986)
    Weinheim : Wiley-Blackwell
    Electrophoresis 7 (1986), S. 134-141 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Micro-polyacrylamide gel electrophoresis (micro-PAGE) has been shown to be useful for molecular size separation of urinary proteins. In addition to the sodium dodecyl sulfate micro-gradient gel electrophoresis in 10 μL capillaries, which is used routinely for examination of proteinuria in our laboratory, we tried micro-gradient slab gel electrophoresis (micro-slab-PAGE) for molecular weight determination of urinary proteins. It was also employed for monitoring patients with proteinuric diseases. For detailed studied of urinary proteins, micro-two-dimensional-electrophoresis is recommended.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150070306
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  • 5
    Electronic Resource
    Electronic Resource
    Polyacrylamide gel electrophoresis of small peptides (1984)
    Weinheim : Wiley-Blackwell
    Electrophoresis 5 (1984), S. 133-138 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two polyacrylamide gel electrophoretic systems for the separation of small peptides are described. In both systems the samples are concentrated by a buffer discontinuity, and the peptides separated according to size and charge in 40-50 % polyacrylamide resolving gels. The acidic gel has an operative pH between 3.0 and 3.1 while the alkaline gel has an operative pH between 9.1 and 9.2. The lower limit of resolution is about 100 daltons for a peptide with one positive charge in the acidic system. The radioactive peptides are detected by autoradiography. Peptides with a free amino group can be fixed in these gels with formaldehyde, so that fluorographic procedures can also be used for increased sensitivity. These techniques enable precise comparison of non-derivatized peptides from complete protein fingerprints and offer a simple one-dimensional analytical method for protein comparison, as well as a general method for separating and analyzing small peptides.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150050302
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  • 6
    Electronic Resource
    Electronic Resource
    Metabolism of 1,1,1,2,2-pentafluorohexane and 1,1-difluorocyclohexane by rat liver microsomes in vitro (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 512-521 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolism of 1,1,1,2,2-pentafluorohexane with liver microsomes from phenobarbital-treated rats gave only one metabolite, namely, the 5-hydroxy derivative. Under similar conditions 1,1-difluorocyclohexane was metabolized to give mainly the 3- and 4-hydroxy derivatives in the ratio 1:∼5.5 The structures of these metabolites were established by chemical ionization (CI) and/or electron impact (EI) mass spectrometry and confirmed by synthesis in the case of 1,1-difluorocyclohexan-4-ol. Oxidation of 1,1-difluorocyclohexane with lead tetrakis(trifluoroacetate) also gave, inter alia, the 3- and 4-hydroxy derivatives. In saturated hydrocarbons complete replacement of hydrogen by fluorine at one particular carbon will not only block microsomal hydroxylation thereat but will also inhibit hydroxylation at neighbouring hydrogen-bearing carbons, (α almost completely, β markedly, γ slightly).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200111005
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of the antibody response to bee venom phospholipase A2 induced by natural exposure in humans or by immunization in mice (1997)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 10 (1997), S. 93-100 
    Details
    ISSN: 0952-3499
    Keywords: monoclonal antibodies ; human ; antigen ; mouse ; allergen ; phospholipane ; epitope mapping ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Two human and twelve murine monoclonal antibodies directed against the main bee venom allergen phospholipase A2 (PLA) were evaluated for their fine specificity of binding to antigen and their ability to inhibit the enzymatic activity of the antigen. Antibodies were induced by natural exposure of beekeepers to bee venom or immunization of mice via different methods. Both human monoclonal antibodies (hmAbs) were previously shown to recognize the native three-dimensional conformation of PLA and are directed against discontinuous epitopes which include lysine residue at position 25 as a contact residue. In contrast, six of the murine monoclonal antibodies (mmAbs) bind to the denatured structure of the protein as determined by enzyme-linked immunosorbent assay. The epitopes recognized are located near the C-terminal end (n=8), in the centre of the polypeptide (n=1), near the N-terminal end (n=1) or include the carbohydrate part (n=2) of the PLA molecule. The capacity of the antibodies to modify the enzymatic activity was also determined. The hmAbs significantly inhibit the enzyme (70-79%), whereas the mmAbs produced various degrees of inhibition (39-100%). Since the X-ray structure of PLA is known, the epitopes can be visualized in the context of the three-dimensional structure of the antigen. A qualitative correlation was found between the location of epitopes and the inhibition pattern. Strong inhibition was seen with those antibodies that recognize epitopes that lie on the surface of the enzyme that is thought to contact the phospholipid bilayer. The results show that even though both hmAbs and most mmAbs inhibit the enzymatic activity of PLA, the antigen-binding properties of antibodies from different species raised after different routes of immunization differ significantly. Thus, detailed epitope mapping studies using murine antibodies prepared by artificial immunization may have limited value in predicting epitope patterns relevant to an antibody response to allergens in humans naturally exposed to antigen/allergen. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Octafluorotoluene as a derivatizing agent for steroids in human plasma (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 211-213 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of octafluorotoluene (OFT) as a versatile gas chromatographic/mass spectrometric derivatizing agent for steroids containing alcoholic, phenolic or α,β-unsaturated keto functions, is described. Two distinct derivatizing schemes can be utilized, involving (method 1) a phase-transfer reaction, employing a two-phase system of CH2Cl2 and N NaOH with n-Bu4NHSO4 as catalyst (suitable for alcoholic and phenolic steroids) and (method 2) a reaction conducted in anhydrous dimethylformamide at 155°C with CsF as base (appropriate for α,β-unsaturated keto steroids). Perfluorotolyl (PFT) ethers and/or enol ethers have thus been generated. The electron impact spectra display abundant high-mass molecular ions where derivatization has occurred at a phenolic or enolic function. An extraction, derivatization and gas chromatographic/mass spectrometric scheme has been devised involving method 2 for the analysis of steroids in human plasma. A preliminary quantitative investigation of the levels of testosterone in plasma has been carried out employing these methods. The anomalously high level found is explained in terms of the presence in plasma of lipid-soluble derivatives of testosterone (probably fatty acid esters) which generate the testosterone bis-OFT derivative under the reaction conditions employed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200160138
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  • 9
    Electronic Resource
    Electronic Resource
    Confirmation of oxytetracycline, tetracycline and chlortetracycline residues in milk by particle beam liquid chromatography/mass spectrometryThis work was presented in part at the 38th ASMS Conference on Mass Spectrometry and Allied Topics, Tucson, Arizona, June 1990. (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1991), S. 789-795 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method using particle beam liquid chromatography/mass spectrometry was developed for the confirmation of oxytetracycline, tetracycline and chlortetracycline residues in bovine milk. This method is one of the first to apply particle beam technology to the confirmation of animal drug residues in food products for regulatory purposes. The milk is centrifuged, using molecular weight cut-off filters to remove components of 25 000 daltons and above from the milk. The filtrate is passed through a C-18 sample preparation cartridge which retains the tetracyclines. After the columns are washed with water, the tetracyclines are eluted with 0.1 M oxalic acid in methanol and concentrated. The compounds are separated on a Novapak C-18 column with a methanol-oxalic acid-acetonitrile mobile phase. Negative chemical ionization with selective ion monitoring is used to identify the tetracyclines. The procedure was used to confirm the presence of each tetracycline at 100 ng ml-1 in fortified and incurred milk samples.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200201208
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  • 10
    Electronic Resource
    Electronic Resource
    Analysis of mercapturic acid conjugates of xenobiotic compounds using negative ionization and tandem mass spectrometryPresented in part at the 36th Annual Conference on Mass Spectrometry and Allied Topics, San Francisco, 1988. (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 68-76 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of mercapturic acid conjugates of two xenobiotic products of lipid peroxidation (trans-4-hydroxy-2-hexenal and trans-4-hydroxy-2-nonenal) as well as conjugates of 1,3-dichloropropene, styrene oxide, 1,2-naphthalene oxide and α-chlorotoluene were obtained using fast atom bombardment or negative chemical ionization. Fragmentation pathways were investigated using linked scan and mass-analyzed ion kinetic energy spectrometric techniques. Characteristics of the spectra obtained using different ionization and sample introduction techniques are compared. Deprotonated molecular ions of mercapturic acids gave simple daughter ion spectra, with the dominant mode of decomposition involving cleavage of C—S bonds giving a characteristic neutral loss of 129 Da Screening for mercapturates in urine samples was performed using neutral loss scanning and yielded limits of detection in the low nanogram per milliliter range. Quantitative analysis of the S-benzyl mercapturic acid at 1 p.p.b. in urine has been demonstrated using combined gas chromatography/electron capture mass spectrometry with d3-S-benzyl mercapturic acid as internal standard.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200220109
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