Investigating Interaction Dynamics of an Enantioselective Peptide Catalyzed Acylation Reaction

Nuclear magnetic resonance (NMR) is a key method to investigate molecular recognition in biomacromolecules and to detect molecular motions on the µs to s timescale revealing transient conformational states. Changes in kinetics of interconversions between those states can be linked to binding, folding or catalytic events. Here, we investigated whether these methods allow detection of changes in the dynamics of a small, highly selective peptide catalyst during recognition of its enantiomeric substrates. The flexible tetrapeptide Boc-L-(π-Me)-His-AGly-L-Cha-L-Phe-OMe, used for the monoacetylation of cycloalkane-diols, is probed at natural abundance using carbon relaxation dispersion in the rotating frame (13C-R1ρ) and proton chemical exchange saturation transfer (1H-CEST). Indeed, we detected differences in dynamics of the peptide upon interaction with the diol. Importantly, these differ depending on the enantiomer of the substrate used providing insights into the recognition of the substrates. These enantiospecific influences of the substrates on the dynamics of the peptide catalyst revealed are rationalized using. computational techniques. Moreover, findings obtained are supported by experimental reaction monitoring of the acetylation reaction.