Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9573490 | Biophysical Chemistry | 2005 | 8 Pages |
Abstract
Unfolding intermediates have been found only rarely in earlier studies, and how a protein unfolds is therefore poorly understood. In this paper, we show experimental evidence for multiple pathways and multiple intermediates during unfolding reaction of O6-methylguanine-DNA methyltransferase from hyperthermophile Thermococcus kodakaraensis (Tk-MGMT). The unfolding profiles monitored by far-UV CD and tryptophan fluorescence were both biphasic, and unfolding monitored by fluorescence was faster than that monitored by CD. GdnHCl-induced titration curves indicate that the intermediates with significant α-helical structure accumulate during unfolding. Dependence of kinetic phases on initial GdnHCl concentrations and cysteine reactivity of Tk-MGMT were investigated, suggesting that the heterogeneity of native conformations and parallel unfolding pathways.
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Shingo Nishikori, Kentaro Shiraki, Shinsuke Fujiwara, Tadayuki Imanaka, Masahiro Takagi,