Kidney stone rarity in South Africa's black population : investigation of the biochemical and physico-chemical properties of Tamm Horsfall Mucoprotein as a possible contributory factor
Doctoral Thesis
2004
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University of Cape Town
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Abstract
Tamm Horsfall mucoprotein (THP) is a powerful inhibitor of calcium oxalate crystallisation. Since urolithiasis in South African blacks is extremely rare, this study was undertaken to compare the relative inhibitory and biochemical properties of this protein in South African black and white healthy and stone—forn1ing male subjects. THP was isolated by salt precipitation, purified by column chromatography and verified by electrophoresis on SDS-polyacrylamide gels. MALDI-TOF mass spectroscopy was used to determine the molecular weights of the protein from each group and their respective amino acids were analysed. All four THP groups were subjected to tryptic finger printing digestion and matched those of the database. The secondary structures of the four THP proteins were also determined using circular dichroism. The carbohydrate moeities of the four THP groups were analysed for and O-linked oligosaccharides. THP from each of the four groups were subjected to a series of crystallisation experiments using a crossover design in which the protein was added to the urine from which it had been originally isolated, as well as to the urines from the other three groups. This process generated a 4x4 protein-urine grid for investigation of the inhibitory properties of THP in different urine environments. Calcium oxalate crystallization was induced by administration of aqueous sodium oxalate and was monitored Using a Coulter Counter. In another series of experiments 14C-oxalate was used to initiate crystallization. Monitoring in these experiments was achieved by scintillation counter techniques. Calcium oxalate crystal aggregation was investigated in the presence and absence of THP using zeta potential measurements and crystal sedimentation experiments.
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Craig, T. 2004. Kidney stone rarity in South Africa's black population : investigation of the biochemical and physico-chemical properties of Tamm Horsfall Mucoprotein as a possible contributory factor. University of Cape Town.