Thermodynamic dissection of large-scale domain motions coupled with ligand binding of enzyme I.

ABSTRACT: Domain motions are central to the biological functions of many proteins. The energetics of the motions, however, is often difficult to characterize when motions are coupled with the ligand binding. Here, we determined the thermodynamic parameters of individual domain motions and ligand binding of enzyme I (EI) using strategic domain-deletion mutants that selectively removed particular motions. Upon ligand binding, EI employs two large-scale domain motions, the hinge motion and the swivel motion, to switch between conformational states of distinct domain-domain orientations. Calorimetric analysis of the EI mutants separated the free energy changes of the binding and motions, demonstrating that the unfavorable hinge motion (ΔG = 1.5 kcal mol(-1)) was driven by the favorable swivel motion (ΔG

SUBMITTER: Yun YJ 

PROVIDER: S-EPMC3831675 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature