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  • 1
    ISSN: 0947-6539
    Keywords: helical structures ; heme proteins ; iron ; peptides ; synthesis design ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we describe the design, synthesis, and spectroscopic characterization of a covalent helix-heme-helix sandwich named FeIII mimochrome I. It contains deuterohemin bound through both propionyl groups to two identical N-and C-terminal protected nonapeptides as α-helical scaffolds. Each peptide moiety bears a His residue in the central position, which acts as axial ligand to the metal ion. The newly developed synthetic strategy is based on a combination of solution and solid-phase methodologies. It represents a powerful method for obtaining a large variety of analogues containing two symmetric or unsymmetric peptide chains covalently bound to the deuteroporphyrin ring. UV/Visible spectroscopic characterization in buffered 2,2,2-trifluoroethanol/water solution proves low-spin bis(his-tidine) iron(III) coordination; circular dichroism (CD) measurements show an α-helical conformation for the peptide moieties. Thus, all the data are in agreement with the designed hypothetical model regarding both the iron(III) coordination and the peptide chain structural organization.
    Additional Material: 9 Ill.
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  • 2
    ISSN: 0947-6539
    Keywords: cobalt ; helical structures ; heme proteins ; NMR spectroscopy ; por-phyrinoids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: FeIII mimochrome I is the prototype of a new class of hemoprotein models characterized by a covalent helix-heme-helix sandwich. It contains deuterohemin bound through two propionyl groups to two identical N- and C-terminal protected α-helical nonapeptides, each of which bears a His residue (a potential axial lig-and of the iron ion) in the central position. In order to understand better the three-dimensional structure of FeIII mimochrome I and its correlation with spectral properties, we have characterized the fully diamagnetic parent compound CoIII mimochrome I by UV/visible, CD, and NMR spectroscopy, coupled with conformational energy calculations. CoIII mimochrome I is a highly water-soluble compound present in solution as two isomers, which slowly interconvert only at very low pH values. These isomers were isolated and separately characterized. Their UV/visible spectral properties are very similar, while their CD spectral properties differ markedly in both the far UV and Soret regions. The isomers were identified by 1H NMR spectroscopy as diastereomers of the δ and δ type. This is the first example of an accurate three-dimensional structure determination in solution of a hemoprotein mimetic that allows a straightforward correlation between structure and spectral properties.
    Additional Material: 13 Ill.
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  • 3
    ISSN: 0935-6304
    Keywords: Organochlorine compounds ; pesticides ; food analysis ; tomatoes ; GLC-ECD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A method is described for the simultaneous extraction and determination of twenty organochlorine pesticides residues [hexachlorocyclohexane (HCH) isomers (α, β, γ, δ), aldrin, dieldrin, endrin, heptachlor and its epoxide (HE), hexachlorobenzene (HCB), α-endosulfan, o,p′-DDD, p,p′-DDD, o,p′-DDE, p,p′-DDE, o,p′-DDT, p,p′-DDT, dicofol, methoxychlor, and mirex] that were spiked in tomatoes. Samples were extracted with ethyl acetate, and the extract was subjected to a rapid clean-up using a Florisil column. The residues were determined by GLC-ECD using two columns of different polarity. The calibration graph correlation coefficient ranged from 0.9903 to 0.9990. The recoveries ranged from 95 to 99% with relative standard deviation ranging from 0.5 to 14.7% in the concentration range 0.005 to 0.2 μg/g. The limits of detection ranged from 0.004 to 0.05 μg/g and the limits of quantification ranged from 0.005 to 0.174 μg/g.
    Additional Material: 1 Ill.
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  • 4
    ISSN: 0935-6304
    Keywords: Adhesives ; GC/MS ; headspace analysis ; poly(vinyl acetate) ; volatile organic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 183-185 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Ethylene glycol ; Migration ; Foods or food simulants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 6
    ISSN: 0935-6304
    Keywords: HPLC ; di(2-ethylhexyl) phthalate ; migration ; foods and food simulants ; PVC cling film ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 37 (1995), S. 401-410 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two cyclic and branched peptides (PLA and AZU) were synthesized with the aim of reproducing the active site of the blue copper proteins plastocyanin and azurin. Both peptides, designed on the basis of the x-ray structures of Poplar plastocyanin and Alcaligenes denitrificans azurin. contain the same coordinating residues of the parent native proteins. The visible spectra of PLA in the presence of equimolar amount of Cu(II) strongly support the interaction between the peptide and copper(II) ion. The CD titration of AZU with the Hg(II) ion indicates for the formation of two species. [A ZUHg]+ and [A ZUHg2]3+ having binding constants (Keq) of 3.106 and 2-104M-1, respectively. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 396-398 
    ISSN: 1040-0397
    Keywords: Metallothioneins ; Cathodic stripping voltammetry ; Metal-binding proteins ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A cathodic stripping voltammetric method for the determination of metallothioneins (MT) is proposed. The procedure is based on the controlled adsorption of the protein on the mercury electrode after addition of an excess of CuII to the solution. The effects of accumulation time, adsorption potential and copper concentration have been examined and the analytical procedure has been optimized. Using an accumulation time of 300 s, a MT concentration of 0.2 nM can be detected.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 3 (1997), S. 241-249 
    ISSN: 1075-4261
    Keywords: NMR ; vibrational spectroscopy ; 5-bromouridine ; base pairing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A multinuclear magnetic resonance and vibrational study on 5-bromouridine and its base pairing with guanosine and adenosine in deuterated dimethyl sulfoxide at different concentrations is reported. A dicarbonylic non-self-associated form is suggested for 5-bromouridine on the basis of the 1H-, 15N-NMR, and Raman data. When guanosine is added in equimolar amounts, a downfield shift of the (N3)H proton of 5-bromouridine and of the (N1)H and NH2 protons of guanosine is observed; these results can be interpreted, according to the Raman ones, considering that only a fraction of guanosine is “wobble base paired” with 5-bromouridine, whereas the remaining part is self-associated. When 5-bromouridine is mixed with adenosine, the proton chemical shift of the aminic NH2 of adenosine increases and the (N3)H iminic of 5-bromouridine moves downfield at a value higher than that observed for the 5-bromouridine-guanosine mixture. This behavior supports the hypothesis that 5-bromouridine interacts more with adenosine than with guanosine, but the results obtained are not able to establish which type of pairing (Watson-Crick or Hoogsteen) is present. Finally, the infrared spectrum of the solid 5-bromouridine: adenosine adduct, for which X-ray measurements of other authors suggested a Hoogsteen pairing, is reported and the observed bands are discussed. © 1997 John Wiley & Sons, Inc. Biospect 3: 241-249, 1997
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0730-2312
    Keywords: monomeric laminin receptor ; shedding ; metastasis ; double determinant assay ; adhesion ; prognostic factor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The 67-kD laminin receptor (67LR) is a cell membrane-associated molecule exhibiting high affinity for the basement membrane glycoprotein, laminin. While export of the 67LR toward the extracellular matrix has been recently suggested by electron microscopy studies, there is to date no evidence of shedding of the 67LR from cells. Using two monoclonal antibodies directed against the 67LR, we developed a double-determinant radioimmunoassay that demonstrates that the 67LR is released from cancer cells into the culture medium. The shed molecule exhibited the same apparent molecular weight as that of the membrane-associated 67LR, suggesting that no proteolytic cleavage is involved in the process. Furthermore, we demonstrate that the 67LR is not anchored to the membrane through a glycolsyl-phosphatidylinositol bridge. However, the observation that lactose increased the release of 67LR suggests that a lectin-type interaction is involved in the cell membrane association of this laminin binding protein and the cell surface. Interestingly, the released 67LR recovered after HPLC gel filtration was found free as well as associated to high molecular weight complexes. The free 67LR retained its ability to bind to the cell surface. Our study is the first demonstration that the 67LR is effectively shed by cancer cells. The released free 67LR could play an important role in modulating interactions between cancer cells and laminin during tumor invasion and metastasis. © 1996 Wiley-Liss, Inc.
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