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Studies of ferritin and haemosiderin from β-thalassaemia/Haemoglobin E tissues

Tran, Kim Chi Thi (1991) Studies of ferritin and haemosiderin from β-thalassaemia/Haemoglobin E tissues. PhD thesis, Murdoch University.

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Abstract

Ferritin and haemosiderin have been isolated from the liver, spleen, heart and pancreas of patients with β-thalassaemia/Haemoglobin E, (β-thal/HbE) and from the liver and spleen of normal patients and horse spleen. The physical structure and chemical reactivity of these iron-containing proteins have been examined using a variety of techniques. The protein-shell structure of ferritin from all β-thal/HbE organs examined appeared to be very similar when examined using PAGE, SDS-P AGE and isoelectric focussing. In all cases, the major subunit present was the L subunit. However, considerable differences were found among the iron cores using transmission electron microscopy, electron diffraction and Mossbauer spectroscopy. Thus, ferritin cores from β­thal/HbE heart and pancreas were found to have a larger size, a greater degree of crystallinity and a higher superparamagnetic blocking temperature than those from normal liver and spleen. β-thal/HbE liver and spleen ferritin cores were found to be smaller and less crystalline and to have a lower superparamagnetic blocking temperature. The structure of the iron-containing cores can be correlated with the use of this protein for long-term iron storage in heart and pancreas and with a shorter turnover time in the liver and spleen in β-thal/HbE disease.

Haemosiderin cores have also been characterized by Mossbauer spectroscopy and diffraction techniques. The data indicate that three different types of haemosiderin core can be identified: (1) a poorly crystalline goethite-like material possessing the highest superparamagnetic blocking temperature; (2) a ferrihydrite-type material with a lower superparamagnetic blocking temperature and (3) an amorphous material with a magnetic order/disorder transition below 4K. Iron in the cores of haemosiderin from β-thal/HbE liver and pancreas was mainly in the form of type 2 with a minor component of type 1 and a trace of type 3. In contrast, iron in haemosiderin from β-thal/HbE heart and spleen was found to be type 3, although trace amounts of types 2 and 1 may also be present

Haemosiderin from the pathological samples released iron to the chelating agent desferrioxamine B much faster than ferritin, presumably due to the presence of the less crystalline ferrihydrite-type and amorphous material in the core, and also due to the limited nature of the protein shell. Generally the more crystalline protein cores were found to bind the iron more tightly under the conditions of this assay. The results obtained for both ferritin and haemosiderin have been considered in light of the pathology and ferrokinetics of the disease which affects large numbers of people in South-East Asia.

Item Type: Thesis (PhD)
Murdoch Affiliation: School of Biological and Environmental Sciences
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: repository@murdoch.edu.au. Thank you.
Supervisor(s): Webb, John and Macey, David
URI: http://researchrepository.murdoch.edu.au/id/eprint/52149
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