Histidine's ability to adopt two different charge states at physiological pH, and its unique and direct interactions with H-bond donors and acceptors and other charged species, mean that His plays a central and irreplaceable electrostatic role in many proteins.  With the determination of the charge state and interactions of specific histidine residues in arbitrarily complex proteins and protein assemblies as a goal, we recently developed the carbon-deuterium stretching vibration of 2-deuterated histidine as a vibrational reporter using Raman spectroscopy.  Following a classic heterocyclic H-D exchange mechanism, any solvent-exposed His residue can be 2-deuterated by simply placing the protein in D2O and gently heating the sample.  The C2-D bond then is stable for very long periods of time, and the unique C2-D stretching frequency reports directly on both the charge state and noncovalent interaction partners of the labeled His residue.  The specific sensitivity of this unique vibration has been mapped out using model compounds. Strategies for incorporation and observation of this new vibrational probe group into several proteins will be presented, as well as the sorts of electrostatic problems that might be most directly addressed using this post-translational isotopic substitution strategy.

Protonation state and noncovalent interactions of histidine reported by a carbon-deuterium stretching vibration

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.