title: D/H amide isotope effect in model alpha-helical peptides.
abstract: The contribution of amide related hydrogen bonds to protein stability has recently been evaluated using the "Cm experiment", which measures the D/H amide isotope effect in proteins. We show here using isolated alpha-helical peptides that there is a significant effect of denaturant concentration on the measured D/H isotope effect, and that valid comparison of different proteins requires correcting for differences in denaturant (GdmHCl) concentration. Finally our results suggest that H-bonds in an isolated alpha-helix may contribute more to helix stability because of less strain compared to those in helical proteins and that the buried helical H-bonds in helical proteins are not necessarily energetically more favorable than solvent exposed H-bonds in isolated helices.
authors.affiliation: Department of Chemistry, New York University, 100 Washington Place, New York, NY 10003, USA.
authors.forename: Zhengshuang
authors.initials: Z
authors.lastname: Shi
authors.forename: C Anders
authors.initials: CA
authors.lastname: Olson
authors.forename: Neville R
authors.initials: NR
authors.lastname: Kallenbach
authors.forename: Tobin R
authors.initials: TR
authors.lastname: Sosnick
mesh_terms: D000409:Alanine / Q000737:chemistry; D000577:Amides / Q000737:chemistry*; D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004268:DNA-Binding Proteins; D003903:Deuterium / Q000737:chemistry; D019791:Guanidine / Q000737:chemistry; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011494:Protein Kinases / Q000737:chemistry; D017433:Protein Structure, Secondary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry
chemical_list: D000577:Amides; D004268:DNA-Binding Proteins; D010455:Peptides; D029701:Saccharomyces cerevisiae Proteins; D003903:Deuterium; D011494:Protein Kinases; D019791:Guanidine; D000409:Alanine