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[PAST EVENT] Wei Xu: Applied Science Dissertation Defense
August 21, 2014
2pm - 4pm
Abstract:
The purpose of devising and validating models for intramolecular motions of FMOC amino acids is to quantify side chain motions in peptides, which play an important role in understanding biological structure-function relations of proteins.
In this thesis, spin lattice relaxation times (T1) of FMOC amino acids were measured under both static and magic angle spinning(MAS) conditions as functions of temperature. A three-site jump model for the methyl group was developed to fit the T1z and T1q anisotropy observed under static conditions. Under Magic Angle Spinning, multiple deuterated sites can be resolved and studied independently. The observation of lower activation energies for internal rotation of deuterated methyl groups in the FMOC derivatives than in the parent amino acids implies a less sterically crowded environment for the methyl rotation process.
Finally, a thermal diffusion model for the spinning rotor was developed to account for unavoidable temperature inhomogeneity introduced by frictional heating in rotating samples. A simplified procedure based on computing spin relaxation times for the single most probable temperature was found to be equally as effective as analyzing the more complex distribution of computed relaxation rates based on the full temperature distribution.
The purpose of devising and validating models for intramolecular motions of FMOC amino acids is to quantify side chain motions in peptides, which play an important role in understanding biological structure-function relations of proteins.
In this thesis, spin lattice relaxation times (T1) of FMOC amino acids were measured under both static and magic angle spinning(MAS) conditions as functions of temperature. A three-site jump model for the methyl group was developed to fit the T1z and T1q anisotropy observed under static conditions. Under Magic Angle Spinning, multiple deuterated sites can be resolved and studied independently. The observation of lower activation energies for internal rotation of deuterated methyl groups in the FMOC derivatives than in the parent amino acids implies a less sterically crowded environment for the methyl rotation process.
Finally, a thermal diffusion model for the spinning rotor was developed to account for unavoidable temperature inhomogeneity introduced by frictional heating in rotating samples. A simplified procedure based on computing spin relaxation times for the single most probable temperature was found to be equally as effective as analyzing the more complex distribution of computed relaxation rates based on the full temperature distribution.
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