Equilibrium and Kinetic folding properties of alpha-helical Greek key protein domains

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Title: Equilibrium and Kinetic folding properties of alpha-helical Greek key protein domains
Author: Chen, Yun-Ru
Advisors: Carla Mattos, Committee Member
A. Clay Clark, Committee Chair
Harold Swaisgood, Committee Member
Dennis T. Brown, Committee Member
Abstract: I have characterized the equilibrium and kinetic folding properties of members of alpha-helical Greek key protein domain, caspase recruitment domains of RICK (RICK-CARD) and procaspase-1 (Pro-1-CARD). At equilibrium, folding of both RICK-CARD and Pro-1-CARD is well described by a two-state mechanism representing the native and unfolded ensembles. The proteins are marginally stable,with the Gibbs free energy of 3.0 and 1.1 kcal/mol and m-values of 1.27 and 0.68 kcal/mol/M for RICK-CARD and Pro-1-CARD, respectively (30 mM Tris-HCl, pH 8, 1 mM DTT, 25 degree Celsius). The folding pathways of RICK-CARD are complex and contain at least two or three non-native conformations. The major folding event of RICK-CARD has a folding rate constant of 30 s⁻¹. Studies on seven mutants of RICK-CARD suggest that the three prolyl residues contribute to its structural stability and folding complexity. The folding of Pro-1-CARD is different than that of RICK-CARD. The folding and unfolding kinetics of Pro-1-CARD are fast but with kinetically trapped intermediates present, which appear to be similar to that of RICK-CARD. The work suggests that different alpha-helical Greek key protein domains fold differently but may share some similar folding pathways.
Date: 2003-11-13
Degree: PhD
Discipline: Biochemistry
URI: http://www.lib.ncsu.edu/resolver/1840.16/3718

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