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Research article2012Peer reviewed

Folding-Reaction Coupling in a Self-Cleaving Protein

Wallin, Goran; Hard, Torleif; Aqvist, Johan


Backbone torsional strain has been implicated as a cause of rate enhancement in a class of autoprocessing proteins performing proteolysis and protein splicing. In the autoproteolytic protein domain SEA, folding and proteolytic activity have experimentally been shown to be coupled with about 7 kcal/mol of folding free energy available for catalysis. Here, we have examined the catalytic strategy of SEA with molecular dynamics simulations, potential of mean force free energy profiles, and B3LYP/6-311G(d,p) density functional calculations. A quantitative estimate of the free energy stored as protein strain (about 8 kcal/mol), that is available for catalyzing the cleavage reaction, is obtained and found to be in excellent agreement with thermodynamic and kinetic data. It is further shown that there is strong coupling between folding and reaction coordinates leading to reactant state destabilization in the direction of folding and transition state stabilization along the reaction coordinate. This situation is different from the preorganized active site model in that the fully folded transition state stabilizing structure is not realized until the reaction barrier is surmounted.

Published in

Journal of Chemical Theory and Computation
2012, Volume: 8, number: 10, pages: 3871-3879

      SLU Authors

    • Härd, Torleif

      • Department of Molecular Biology, Swedish University of Agricultural Sciences

    UKÄ Subject classification

    Biochemistry and Molecular Biology

    Publication identifier


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