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  • Analytical Chemistry and Spectroscopy  (2)
  • Exobiology  (1)
  • 1980-1984  (3)
  • 1
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two unusual sulphur-containing amino acids have been isolated from urine of a baby who died with major physical malformations and failure of growth and development. Sensitive mass spectrometric methods were used to identify the nanomole quantities of the compounds available as S-(2-carboxypropyl)-cysteine and S-(2-carboxypropyl)-cysteamine. Incubation of fibroblasts in either [14C]valine or [35S]cysteine resulted in radioactive labelling of the compounds, suggesting their origin from conjugation of methacrylic acid with cysteine and subsequent decarboxylation of the cysteine conjugate. Specific assay of methacrylyl-CoA hydratase is needed for final proof that this is a new inborn error of that enzyme, but these findings and parental consanguinity make this very likely. It seems possible that methacrylic acid or one of its derivatives may have caused the malformations present in the baby.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theophylline administered orally and (1, 3-15N,2-13C)theophylline administered intravenously in tracer quantities were used to investigate under steady-state conditions the interaction of theophylline with cimetidine in a patient with chronic obstructive pulmonary disease. Both compounds were quantified simultaneously by mass spectral-analysis after solvent extraction and high pressure liquid chromatographic purification of plasma samples. The assay is reliable and accurate to a plasma level of 50 ng mI-1 for the stable isotope tracer with a practical lower limit of detection of 10 ng mI-1.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2019-08-15
    Description: A series of porphyrins and catalysts has been prepared as a model for the origin of photosynthesis on the primordial earth. These compounds have been used to test the hypotheses that (1) the biosynthetic pathway to chlorophyll recapitulates the evolutionary history of photosynthesis, and (2) the proto-photosythetic function of biogenetic porphyrins (biosynthetic chlorophyll precursors) was the oxidation of organic molecules by photoexcited porphyrins with the attendant emission of molecular hydrogen. This paper describes experiments in which photoexcited biogenetic porphyrins oxidize ethylenediamine tetraacetic acid (EDTA). The concomitant reduction of protons to hydrogen gas occurs in the presence of a colloidal platinum catalyst. The addition of methyl viologen, a one-electron shuttle, increases the amount of molecular hydrogen generated during long irradiations and the quantum yield of hydrogen production. When the porphyrin and catalyst are held in association by molecular complexes, the increased efficiency of electron transfer produces higher yields of hydrogen gas.
    Keywords: Exobiology
    Type: Photochemistry and photobiology (ISSN 0031-8655); 39; 3; 397-405
    Format: text
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