Structure of the dipeptide L-lysine-L-leucine·Acetate, 0.5 acetic acid hemihydrate

2(C12H26O3N3·C2H3O2)·C2H4O2·H2O,M r =350.44, triclinic, P1,a=5.576,b=12.574(3),c=14.946(2) A, α=107.80(2), β=96.34(2), γ=89.89(2)°.B=991.04(6) A3,Z=2,D x =1.201 g/cm3, λ(KαCu)=1.5418, A, μ=7.4 cm−1, room temperature.R=0.074 for 2645 observed reflections. In the unit cell there are two peptide molecules, three acetic acid molecules, two of them likely to be present as acetate anions, and one water molecule. Each peptide exists in zwitterionic form with the carboxylic group deprotonated, and with positive charges both in the amino terminal and ∈-amino groups of lysine. The two peptide molecules have almost identical conformations. The dipeptide backbone is folded.