title: Retroinverso mimetics of S peptide.
abstract: The S peptide from ribonuclease S was used as a model system to explore the relationship between the native peptide and its retroinverso (RI) analog. As probed by circular dichroism, the conformations of S peptide and retroinverso S peptide (RIS peptide) are each right-handed helical conformation. The helical propensity of retro S peptide is greater than S peptide, in trifluoroethanol (TFE). In 70% TFE, the S peptide possesses greater helicity at pH 4 than at pH 7, whereas RIS peptide possesses greater helicity at pH 7 than at pH 4. The RIS peptide does not mimic the S peptide in binding to S protein. Specifically, the RIS peptide does not mimic the S peptide to effect RNase activity with S protein and it also does not inhibit the RNase activity of S peptide with S protein. The biological mimicry between the S peptide and its RIS analog depends on the conformation and relatedness of both the side chain and backbone substructures. The backbones in the S peptide and its RIS analog are reverted with respect to each other; however, the side chain patterns are predicted to be similar. Importantly, if the molecular interactions of backbone atoms of the S peptide and its binding to S protein, then the RIS analog would be unlikely to mimic this parent peptide.
authors.forename: Jagdish
authors.initials: J
authors.lastname: Rai
mesh_terms: D000818:Animals; D040761:Biomimetic Materials / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012260:Ribonucleases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D013329:Structure-Activity Relationship; D014270:Trifluoroethanol / Q000737:chemistry
chemical_list: D004791:Enzyme Inhibitors; D010455:Peptides; D014270:Trifluoroethanol; D012260:Ribonucleases; C022542:ribonuclease S