Table ). The effects of both Glu73 N-Myc substitutions on potency were subtle, suggesting that this side chain does not make a major contribution to binding. We then assessed the effects of sequence elongation at the C-terminus, by preparing N-Myc73-94 and N-Myc73-97, with C-terminal elongations of five and eight residues, respectively (Table ). Overall, the results indicate that the five residues beyond Gly89 N-Myc contribute little to binding, as only further elongation of the sequence increased potency (N-Myc73-97, IC50 = 79 ± 4 μM).