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The formation of amyloid-beta fibrils within the human brain has shown to be a possible cause for Alzheimer’s disease. Amyloid fibrils can also be formed from various non-disease causing proteins. In this study, in vitro formation of amyloid fibrils from bovine gamma globulin and the subsequent degradation provided an exploration of amyloid fibril properties. Two serine proteases, trypsin and pepsin were studied. The fibril formation from bovine gamma globulin at pH 2 was monitored using thioflavin T (ThT), which is known to bind amyloid fibril to form a complex, which gives off fluorescence. The excitation wavelength used was 420 nm with an emission wavelength of 482 nm. The proteases were subsequently added to the pre-formed amyloid fibril to induce degradation. Pepsin’s properties allowed for the pH of the fibril networks to remain at 2, while for trypsin an adjusted pH of 7 ensured that the trypsin molecules would be active. Changes in fluorescence of the ThT-gamma globulin amyloid complex confirmed that degradation occurred to the amyloid fibril. The rate constant and the half-life for the degradation were calculated to compare influences from changes in pH to that of the proteases. Final half-life calculations for degradation of the amyloid fibril came to be 1.3 hours for pepsin, 9.2 hours for the pH change from 2 to 7, and 14 hours for trypsin. Calculations show that pepsin at pH 2 had significantly catalyzed degradation faster than trypsin or changes in pH. Future studies will expand the exploration of these degradation processes for amyloid-beta fibril and applications for developing potential anti-amyloid agents.

Content Notes

Poster, Final Report Form

First Advisor

Myoung Lee



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