Interactive computer graphics and chem. synthesis were used as complementary tools for the study of peptide conformation; the Merk Mol. Modeling System was applied to the display of structures and the study of their 3-dimensional properties. Computer modeling was used for a comparison of Types I and II' β-turn conformations of Ac-Ala-Ala-NHMe. The use of γ-, δ-, and ε-lactams were studied, and synthetic routes to lactams I (Boc = Me3CO2C; R = H, CH2CHMe2), II (n = 1, 2), and III were devised. Computer superposition illustrated a good correspondence between the backbones of the proposed LH-releasing hormone β-turn and the β-lactam. Computer modeling was applied to cyclic hexapeptide lactams IV (n = 0, 1, 2). Enkephalin lactam analogs V [X = CH2, CH2CH2, CH2S, lactam configuration = D and L; X = (CH2)3, lactam configuration = D] were prepared, and their biol. activities were dependent on lactam configuration and ring size.