(S)-N-(4-{(S)-1-2-(4-Meth­oxy­benz­amido)-2-methyl­propano­ylpyrrolidine-2-carboxamido}-3456-tetra­hydro-2H-pyran-4-yl)carbon­ylproline dimethyl sulfoxide monosolvate (4-MeBz-Aib-Pro-Thp-Pro-OH)

摘要

The asymmetric unit of the title compound, C28H38N4O8·C2H6OS, contains one tetra­peptide and one disordered dimethyl sulfoxide (DMSO) mol­ecule. The central five-membered ring (Pro²) of the peptide mol­ecule has a disordered envelope conformation [occupancy ratio 0.879 (2):0.121 (2)] with the envelope flap atom, the central C atom of the three ring methylene groups, lying on alternate sides of the mean ring plane. The terminal five-membered ring (Pro⁴) also adopts an envelope conformation with the C atom of the methylene group closest to the carboxylic acid function as the envelope flap, and the six-membered tetra­hydro­pyrane ring shows a chair conformation. The tetra­peptide exists in a helical conformation, stabilized by an intra­molecular hydrogen bond between the amide N—H group of the heterocyclic α-amino acid Thp and the amide O atom of the 4-meth­oxy­benzoyl group. This inter­action has a graph set motif of S(10) and serves to maintain a fairly rigid β-turn structure. In the crystal, the terminal hy­droxy group forms a hydrogen bond with the amide O atom of Thp of a neighbouring mol­ecule, and the amide N—H group at the opposite end of the mol­ecule forms a hydrogen bond with the amide O atom of Thp of another neighbouring mol­ecule. The combination of both inter­molecular inter­actions links the mol­ecules into an extended three-dimensional framework.