title: Cyclo(L-prolyl-L-N-methylphenylalanyl). Conformation in solution and in the crystal.
abstract: Detailed analysis of the proton and carbon-13 NMR spectra of cyclo(L-prolyl-L-N-methylphenylalanyl) in chloroform and methanol in relation to its nonmethylated analog provided information on the conformation of the title compound in solution as well as on the effect of N-methylation and solvation. The X-ray structure of the title compound in the crystalline state showed the same conformational features as the solution structure. The phenyl group folds over the diketopiperazine ring which resembles a flattened half-chair. Both amide bonds are considerably nonplanar. The pyrrolidine ring of proline shows a strong pucker at the ring junction with the largest chi 5 value hitherto observed.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, Prague.
authors.forename: M
authors.initials: M
authors.lastname: Budĕsínský
authors.forename: J
authors.initials: J
authors.lastname: Symerský
authors.forename: J
authors.initials: J
authors.lastname: Jecný
authors.forename: J
authors.initials: J
authors.lastname: Van Hecke
authors.forename: N
authors.initials: N
authors.lastname: Hosten
authors.forename: M
authors.initials: M
authors.lastname: Anteunis
authors.forename: F
authors.initials: F
authors.lastname: Borremans
mesh_terms: D004151:Dipeptides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D014961:X-Ray Diffraction
chemical_list: D004151:Dipeptides; D010456:Peptides, Cyclic; D012996:Solutions; C076490:cyclo(prolyl-N-methylphenylalanyl)