Biophysical studies on the acid denaturation of transthyretin : understanding the mechanism of fibril formation in human amyloid diseases /
The aim of this dissertation is to investigate the mechanism of transthyretin (TTR) amyloid fibril formation by studying wild-type TTR, V30M (the most common FAP-associated variant), and L55P (the most aggressive variant) in an effort to understand the cause of amyloidosis and the mechanism by which...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=727853051&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The aim of this dissertation is to investigate the mechanism of transthyretin (TTR) amyloid fibril formation by studying wild-type TTR, V30M (the most common FAP-associated variant), and L55P (the most aggressive variant) in an effort to understand the cause of amyloidosis and the mechanism by which these mutations lead to early onset disease. Our biophysical studies reveal a common mechanism for the conversion of wild-type, V30M and L55P transthyretin into amyloid fibrils, however the kinetics and thermodynamics of this process differ significantly for L55P-TTR relative to WT and V30M-TTR. In all cases the functional tetrameric form of transthyretin dissociates to an alternatively folded monomeric structure that self-assembles at physiological concentrations into protofilaments and under acidic conditions into filaments and fibrils. The data within present even stronger evidence that the partial acid denaturation of wild type, V30M, and L55P-TTR leads to a conformationally altered monomeric amyloidogenic intermediate that self assembles into amyloid fibrils through a ladder of quaternary structural intermediates. The activation barriers for the formation of the monomeric amyloidogenic intermediate appear to increase in the order of L55P < V30M < wild type TTR employing either acid or thermal denaturation based on time dependent analysis. These results are strictly consistent with GdnHCl and Urea-mediated denaturation studies of wild type, V30M and L55P TTR demonstrating that V30M and L55P are less stable than wild-type TTR and denature three orders of magnitude more quickly than wild type TTR. Hence, the FAP-associated mutations appear to kinetically and thermodynamically destabilize the TTR tetramer, thus increasing the steady-state concentration of the amyloidogenic intermediate, predisposing individuals with these mutations to amyloid fibril formation and disease. This logic is consistent with the age of amyloid disease onset, which is earliest for the most destabilized FAP variant (L55P disease onset [] 20 yrs of age), followed by the FAP variant of intermediate stability (V30M, disease onset [] 35 yrs of age), followed by the wild type protein involved in the senile amyloid disease SSA (wild type TTR, disease onset [] 80 yrs of age). |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xx, 202 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 181-199). |