Browsing by Author "Fazakerley, G V"

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    Conformational studies of some small biological molecules and their interactions with metal ions
    (1976) Russell, Jill Catherine; Fazakerley, G V
    The solid Cu(II) and Co(II) complexes and complex salts of some thiamine analogues have been prepared. Their electronic spectra, I.R. spectra and Magnetic Moments are presented and discussed in terms of suggested coordination geometries for the complexes. In addition the solution conformations of the Gd(III), Dy(III) and Ho (III) complexes of some 3' , 5' cyclic nucleotides were determined quantitatively using NMR line broadening and line shifting techniques. Reactions of Mn(II) with the cyclic nucleotides were used to find the preferred binding sites on the ligands also using line broadening techniques.
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    Heavy metal interactions with nucleic acid derivatives : a nuclear magnetic resonance study
    (1979) Koch, Klaus R; Fazakerley, G V
    The aqueous solution conformation of SAH and SAM has been investigated using lanthanide probes. SAH at pH 7.0 interacts normally with lanthanide aquo ions and lanthanide-EDTA complexes via coordination at the carboxyl group. The conformation of the homocysteine fragment is found to, be extended but bent back towards the adenine base. SAM does not interact with lanthanide aquo ions in the pH region 2-7. It does form complexes with lanthanide-EDTA species via an ion-pairing mechanism rather than direct coordination. In addition to lanthanide probes, 250 MHz 1H n.m.r. spectra yielded vicinal JHH coupling constants from which the ribose conformation in both SAM and SAH could be more accurately determined.
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    Metal complexes of penicillin and cephalosporin antibiotics
    (1975) Jackson, Graham Ellis; Nassimbeni, Luigi R; Linder, P W; Fazakerley, G V
    The interaction between metal-ions and the penicillin and cephalosporin antibiotics have been studied in an attempt to determine both the site and mechanism of this interaction. The solution conformation of the Cu(II) and Mn(II) complexes were determined using an n.m.r, line broadening, technique. The ligands benzylpenicillin, 6-aminopenicillanic acid, cephalothin, cephalexin, ampicillin and thiaproline were used to study the effect of structural changes in the ligand on the structure of the complex. The stability constants of several metal-ions/penicillin complexes were determined potentiometrically. These were correlated with stability constants determined for several related complexes. Finally the kinetics of the Ni(II) substitution reaction with benzylpenicillin, penicilloic acid, ampicillin and thiaproline was studied.
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    Transition metal complexes of tetracyclines
    (1973) Cunningham, David Graham; Pay, M H; Fazakerley, G V
    Forty-one transition metals were studied to observe their complexing properties with the tetracyclines. Four metals were found to form sufficiently strong complexes with the tetracyclines to provide a basis for a rapid, reliable method of assaying the potency of the tetracycline products used in medicine today. Microbiological methods take twenty hours to perform; spectrophotometric methods may be completed within one hour. Twenty-eight of the transition metals showed evidence of complex formation with the tetracyclines; not all of these complexes were found to be suitable for the spectrophotometric assay of the tetracyclines, however. The ligand-metal ratios of some of the transition metal-tetracycline complexes were determined under specified conditions using Job's method. In the concentration range for ligand and metal (3 x 10⁻⁵ M), the 1 : 1 complexes appeared to predominate. Attempts were made to identify the binding sites of the metal ions on the tetracycline molecules, using infra-red spectrophotometry, but the results were inconclusive. The stability constant of one of the transition metal-tetracycline complexes was determined by a potentiometric method. Using this method, the result for the titanium-tetracycline complex was β₁= 3,4 x 10¹⁵ M⁻¹.