{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Chitta RK"],"funding":["NCRR NIH HHS","NIGMS NIH HHS"],"pagination":["1813-20"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC2767204"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["20(10)"],"pubmed_abstract":["We describe the use of H/D amide exchange and electrospray ionization mass spectrometry to study, in organic solvents, the pentadecapeptide gramicidin as a model for protein self association. In methanol-OD, all active H's in the peptide exchange for D within 5 min, indicating a monomer/dimer equilibrium that is shifted towards the fast-exchanging monomer. H/D exchange in n-propanol-OD, however, showed a partially protected gramicidin that slowly converts to a second species that exchanges nearly all the active hydrogens, indicating EX1 kinetics for the H/D exchange. We propose that this behavior is the result of the slower rate of unfolding in n-propanol compared with that in methanol. The rate constant for the unfolding of the dimer is the rate of disappearance of the partially protected"],"journal":["Journal of the American Society for Mass Spectrometry"],"pubmed_title":["The gramicidin dimer shows both EX1 and EX2 mechanisms of H/D exchange."],"pmcid":["PMC2767204"],"funding_grant_id":["2P41RR000954","P41 GM103422","P41 RR000954","P41 RR000954-317532"],"pubmed_authors":["Rempel DL","Gross ML","Chitta RK"],"additional_accession":[]},"is_claimable":false,"name":"The gramicidin dimer shows both EX1 and EX2 mechanisms of H/D exchange.","description":"We describe the use of H/D amide exchange and electrospray ionization mass spectrometry to study, in organic solvents, the pentadecapeptide gramicidin as a model for protein self association. In methanol-OD, all active H's in the peptide exchange for D within 5 min, indicating a monomer/dimer equilibrium that is shifted towards the fast-exchanging monomer. H/D exchange in n-propanol-OD, however, showed a partially protected gramicidin that slowly converts to a second species that exchanges nearly all the active hydrogens, indicating EX1 kinetics for the H/D exchange. We propose that this behavior is the result of the slower rate of unfolding in n-propanol compared with that in methanol. The rate constant for the unfolding of the dimer is the rate of disappearance of the partially protected","dates":{"release":"2009-01-01T00:00:00Z","publication":"2009 Oct","modification":"2025-04-22T01:05:38.066Z","creation":"2019-03-27T00:26:09Z"},"accession":"S-EPMC2767204","cross_references":{"pubmed":["19631556"],"doi":["10.1016/j.jasms.2009.05.017"]}}