Date of Award
1-1-2013
Document Type
Dissertation
Degree Name
Ph.D.
Organizational Unit
Physics and Astronomy
First Advisor
Sean E. Shaheen, Ph.D.
Second Advisor
Kingshuk Ghosh
Third Advisor
David Patterson
Fourth Advisor
Dinah Loerke
Keywords
Adenylosuccinate lyase, Gain in toxic function, Kinetics, Loss of function, Stability
Abstract
Biophysical tools are becoming more useful in approaching human genetic disease. The pathogenic mechanisms behind many disorders have been attributed to protein loss of function or gain in toxic function. For example, changes in the protein Adenylosuccinate Lyase (ADSL) lead to ADSL deficiency, a disorder that causes symptoms ranging from epilepsy to expression of autistic features. Biophysics offers different tools to study intrinsic properties of proteins. We have applied such tools to study the enzyme kinetics and protein stability of ADSL and two mutations (R426H and R303C) to formulate better hypotheses regarding the pathogenic mechanism. Enzyme kinetic findings indicate a) non-linear dependences of the activities on the substrate ratios due to competitive binding and b) distinct differences in the behaviors of the different mutations. Preliminary stability measurements indicate a) there is an intermediate state in the folding pathway and a fourth state is necessary for modeling, b) R426H, a mutation that causes severe phenotypes, is less stable, c) there is no evidence of a gain in toxic function for either mutation. This complete work supports our hypothesis that there are multiple mechanisms of pathogenesis of ADSL deficiency including instability of the functional ADSL tetramer, aggregation of ADSL, or diminution of enzyme activity. The significance of this is that development of an effective therapy may depend upon which mechanism is active in a particular patient.
Publication Statement
Copyright is held by the author. User is responsible for all copyright compliance.
Rights Holder
Stephen P. Ray
Provenance
Received from ProQuest
File Format
application/pdf
Language
en
File Size
276 p.
Recommended Citation
Ray, Stephen P., "Biophysical Approaches to Human Genetic Disease: ADSL Deficiency as a Model" (2013). Electronic Theses and Dissertations. 908.
https://digitalcommons.du.edu/etd/908
Copyright date
2013
Discipline
Biophysics