Quantitative dissection of hydrogen bond-mediated proton transfer in the ketosteroid isomerase active site.

ABSTRACT: Hydrogen bond networks are key elements of protein structure and function but have been challenging to study within the complex protein environment. We have carried out in-depth interrogations of the proton transfer equilibrium within a hydrogen bond network formed to bound phenols in the active site of ketosteroid isomerase. We systematically varied the proton affinity of the phenol using differing electron-withdrawing substituents and incorporated site-specific NMR and IR probes to quantitatively map the proton and charge rearrangements within the network that accompany incremental increases in phenol proton affinity. The observed ionization changes were accurately described by a simple equilibrium proton transfer model that strongly suggests the intrinsic proton affinity of one of the T

SUBMITTER: Sigala PA 

PROVIDER: S-EPMC3710806 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature