Defining protein ensembles with native-state NH exchange: kinetics of interconversion
 

Defining protein ensembles with native-state NH exchange: kinetics of interconversion and cooperative units from combined NMR and MS analysis.

Related Articles Defining protein ensembles with native-state NH exchange: kinetics of interconversion and cooperative units from combined NMR and MS analysis.

J Mol Biol. 1999 Jan 22;285(3):1265-75

Authors: Arrington CB, Teesch LM, Robertson AD

Previous studies of native-state peptide hydrogen atom (NH) exchange in turkey ovomucoid third domain (OMTKY3) yielded the thermodynamics and kinetics of unfolding and folding for the 14 slowest-exchanging peptide hydrogen atoms (NHs). Unfolding rate constants and free energies for nine of the NHs are very similar, suggesting that these NHs exchange during a single cooperative unfolding event. Electrospray ionization mass spectrometry (ESI-MS) has been used to test this hypothesis. ESI-MS data and MS peak simulations suggest that this hypothesis is incorrect: in spite of the similarity in their unfolding rate constants, only three to five of the nine residues exchange in a cooperative manner. Thus, residues with similar thermodynamics and kinetics of exchange are probably involved in multiple conformational equilibria. Overall, combined NMR and MS analysis of NH exchange provides a rich and complex picture of the ensemble properties of native proteins.

PMID: 9887275 [PubMed - indexed for MEDLINE]



Source: PubMed