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Title: Chemical and biological studies of manganese transferrin
Author: Bunyan, Kerry Emma
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2003
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This thesis is concerned with the loading of transferrin with manganese and some of its chemical and biological properties. Manganese is bound to transferrin as Mn(III) with a characteristic ligand (Tyr) to metal (Mn(III) charge-transfer band at a wavelength of 430 nm. Caeruloplasmin is shown to enhance the uptake of manganese from MnC12 by apo-hTf. However binding is often incomplete and slow. A novel method of loading hTf with Mn using KMnO4 is reported. This method leads to rapid uptake and inductively coupled plasma atomic emission spectroscopy (ICP-AES) determinants confirmed the binding of at least two Mn per hTf molecule. The possible oxidising effects of MnO4- on protein amino acid side chains was considered. In model systems MnO4- oxidises methionine to methionine sulfoxide and methionine sulfone. Evidence of structural changes in apo-hTf induced by Mn(III) binding was obtained by studies using [e-13C]Met-hTf. Preliminary work suggests that Mn(III), like several other metals studied, preferentially binds to the C-lobe first, although this may result in an open domain conformation. Fe(III) as Fe(NTA)2 was found to displace Mn(III) from hhTf but displacement was slower when hTf had been loaded using KMnO4 rather than MnCl2. KMnO4 was not able to displace Fe(III) from Fe2-hTf. Attempts to crystallise Mn-hTf to characterise these structural changes proved difficult. Crystals grew but were of poor quality and did not diffract. Many large crystals were obtained from solutions of Fe2-hTf. The crystals were red/orange and ellipsoidal in shape. Of the Fe2-hTf crystals grown, one diffracted to 3.3 Å with the data being complete to 90%, but not enough information was gained for adequate molecular replacement and structural solution.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available