[Structure of molecules of crystalline (Phe1, Ala9)antamanide].

The molecular structure of a [Phe1, Ala9]antamanide complex with four water molecules has been determined by X-ray analysis. The antamanide's analogue, C64H74N10O10.4H2O, crystallizes in the space group P2(1)2(1)2(1) with a = 15.909, b = 28.071 and c = 14.367 A, Z = 4. The molecule contains a pseudo two-fold rotation axis and two intra-molecular NH...O = C bonds of the 5-->1 type, its conformation being similar to that of antamanide. There are inter-molecular H-bonds over the water molecules in the structure.