Structure of a New Cyclotetrapeptide Trapoxin A

C34H42N4O6, Mr = 602.73, triclinic, P1, a = 14.707 (2), b = 15.559 (2), c = 13.026 (1) A, alpha = 112.23 (1), beta = 97.25 (1), gamma = 60.67 (1) degree, V = 2399.1 (6) A3, Z = 3, Dx = 1.251 Mg m-3, lambda(Cu K alpha) = 1.54178 A, mu = 0.71 mm-1, F(000) = 966, T = 295 K, R = 0.042 for 7802 observed reflections [Fo greater than 3 sigma (Fo)]. The structure of trapoxin A was determined as cyclo[-(S)-phenylalanyl-(S)-phenylalanyl-(R)-pipecolinyl- (2S,9S)-2-amino-8-oxo-9,10-epoxydecanoyl-]. There are three crystallographically independent molecules in the cell. These molecules are linked to each other by NH...O hydrogen bonds to form an infinite chain extending along the a axis.