Abstract: | The crystal structure of N‐(l ‐2‐aminobutyryl)‐l ‐alanine, C7H14N2O3, is closely related to the structure of l ‐alanyl‐l ‐alanine, both being tetragonal, while the retro‐analogue 2‐(l ‐alanylamino)‐l ‐butyric acid 0.33‐hydrate, C7H14N2O3·0.33H2O, forms a new type of molecular columnar structure with three peptide molecules in the asymmetric unit. |