title: Lactam restriction of peptide conformation in cyclic hexapeptides which alter rumen fermentation.
abstract: gamma, delta- and epsilon-lactam containing cyclic hexapeptide analogs of cyclo-(Ala-Sar)3 have been prepared by cyclotrimerization. The analogs are covalently bridged between the methyl groups of the alanine and sarcosine residues. Only the delta-lactam of the S configuration shows the same ability as cyclo-(Ala-Sar)3 to inhibit methane production in the fermentation in rumen stomach fluid. The lactam rings of different size therefore offer a sensitive probe of the bioactive conformation of a peptide.
mesh_terms: D000818:Animals; D005285:Fermentation / Q000187:drug effects*; D007769:Lactams / Q000138:chemical synthesis / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000494:pharmacology*; D011487:Protein Conformation; D012417:Rumen / Q000187:drug effects*
chemical_list: D007769:Lactams; D010455:Peptides