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Investigation of the unfolding pathway of Bacillus thuringiensis Cyt2Aa2 toxin reveals an unfolding intermediate

Paper ID Volume ID Publish Year Pages File Format Full-Text
24792 43537 2009 5 PDF Available
Title
Investigation of the unfolding pathway of Bacillus thuringiensis Cyt2Aa2 toxin reveals an unfolding intermediate
Abstract

Cyt2Aa2 is a cytolytic toxin from Bacillus thuringiensis subsp. darmstadiensis. Its active form has a lethal activity against specific mosquito larvae. We characterized an unfolding pathway of Cyt2Aa2 using a guanidinium hydrochloride denaturation. The results revealed three-state transition with a detectable intermediate in a condition with 3–4 M of GuHCl. The conformational free energies for native and intermediate state unfolding were 5.82 ± 0.47 and 16.85 ± 1.47 kcal/mol, respectively. Kinetic analysis suggested that the activation energy of both transitions was around 23–25 kcal/mol, with a rate-limiting step in the second transition. These results have established an energy profile of the Cyt2Aa2 toxin in various conformations involved in the unfolding/refolding pathway. Further characterization of the intermediate state by dye-binding assay, intrinsic fluorescence, and circular dichroism spectroscopy demonstrated characteristics of a molten globule state. This revealed intermediate could play an active role in the structural folding and biological activity of the toxin.

Keywords
Cyt2Aa2; Bacillus thuringiensis; Protein unfolding; Molten globule; Intrinsic fluorescence; Circular dichroism
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Investigation of the unfolding pathway of Bacillus thuringiensis Cyt2Aa2 toxin reveals an unfolding intermediate
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 141, Issues 3–4, 20 May 2009, Pages 137–141
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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Full-text PDF Download
Online Support
Any Questions? feel free to contact us