| Summary: | 碩士 === 國立中興大學 === 生物化學研究所 === 90 === The folding of a protein may be a spontaneous process and independent of its folding path but it may misfold and aggregate. Thus, we designed a stepwise quasi-static process to restore the growth hormone structures and to change refolding potentials of the solvents in a gradual manner in the hope that conformational changes of the associated intermediates, Mi (i = 1 to n), between U and N, might be detected by circular dichroism spectroscopy (CD) and dynamic light scattering (DLS). Conformation analysis of the CD spectra of the refolding intermediates indicated that the secondary structures were restored in the initial refolding intermediate. However, the tertiary interactions within the protein were restored during the last two refolding stages, as elucidated by thermal stability tests. DLS analysis suggested that the average hydrodynamic radii of the refolding intermediates shrunk to native-like-size after the first refolding stage. Our observations suggest that stable protein refolding intermediates can be obtained by using quasi-static TED processes. Namely, an unfolded protein which refolds back through a carefully designed stepwise quasi-static-like process may experience a gradual change in its environment and thus will not be trapped in a “burst phase” or form aggregates.
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