STRUCTURE OF THE DIPEPTIDE L-LYSINE-L-LEUCINE-CENTER-DOT-ACETATE, 0.5-ACETIC-ACID HEMIHYDRATE

2(C12H26O3N3.C2H3O2).C2H4O2.H2O, M(r),= 350.44, triclinic, P1, a = 5.5 76, b = 12.574(3), c = 14.946(2)Angstrom, alpha = 107.80(2), beta = 96 .34(2), gamma = 89.89(2)degrees. B = 991.04(6)Angstrom(3), Z = 2, D-x, = 1.201 g/cm(3), lambda(K alpha Cu) = 1.5418 Angstrom, mu = 7.4 cm(-1 ), room temperature. R = 0.074 for 2645 observed reflections. In the u nit cell there are two peptide molecules, three acetic acid molecules, two of them likely to be present as acetate anions, and one water mol ecule. Each peptide exists in zwitterionic form with the carboxylic gr oup deprotonated, and with positive charges both in the amino terminal and E-amino groups of lysine. The two peptide molecules have almost i dentical conformations. The dipeptide backbone is folded.