AbstractA molecular model for the complex formed between the jack bean lectin concanavalin A (Con A) and glycopeptides of the complex biantennary class is described. The model was derived using coordinates for Con A determined by x‐ray crystalographic refinement techniques, with 1.75‐Å resolution data, and coordinates for the glycopeptides obtained from1H‐nmr measurements, using the nuclear Overhauser effect. Previous solution and crystallographic studies provided several constraints on the possible mode of interaction of the lectin and the glycopeptide. Examination of the model suggests that the glycopeptide binding site is defined by four loops on the protein surface made up by amino acid residues: 12–18, 98–102, 205–208, and 226–229. Within these loops, it favorable interactions with high‐affinity ligands and tose responsible for the unfavourable interactions w