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Title: An investigation of some Australian plants which accumulate transition metals
Author: Mahmoud, Isam El-Din Abdel Wakil
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1982
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Plant samples of three Australian species which grow on mineralized sites in Australia were investigated. In one of these, Hybanthus floribundus, extremely high nickel concentrations were found, particularly in the leaves, which were associated with pectic carbohydrates. Histochemical studies demonstrated a remarkable concentration of nickel in the epidermal layer which corresponded to those areas which gave a positive test for pectin. Mesophyll and palisade cells showed no evidence of nickel concentration, whereas the phloem elements gave a moderate staining. For the other species, Triodia pungens, high zinc was found in its tissues as well as high levels of the amino acid proline. Chromatographic studies show that zinc is associated with pectin and not with proline. Aerial parts of Eriachne mucronata had lower zinc concentrations than Triodia pungens, and the metal was water soluble and present apparently as zinc ion. Chemical extraction schemes carried out on leaves of Hybanthus floribundus showed that 87% of the nickel was associated with pectic and similar polysaccharidic material, 3.34% was solubilized by the proteolytic enzyme pronase and 7.07% of the metal was removed with low molecular weight water soluble materials. For Triodia pungens the corresponding figures were: 76.37%, 3.43% and 16.13% respectively. Mechanisms by which the two plants tolerate their high metal burdens are suggested. Complete amino acid profiles for the three species are reported and discussed. Phenolic compounds present in Hybanthus floribundus were examined, these include a yellow pigment accumulated in large quantities by the plant. The probable structure of the pigment deduced from spectral measurements is suggested. The interaction between pectin with Cu(II), Ni(II), Zn(II) andCo(II) has been studied with the aid of ESR, NMR, electronic and IR spectroscopy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic Chemistry