Figure 7.

Calculated binding pose of Ile-Pro-Ile within the active site of porcine dipeptidyl peptidase IV (DPP-IV). The protein is represented in cartoon, while the amino acids constitutive of the binding site (yellow) and Ile-Pro-Ile (white) are shown in sticks. The white, blue, and red meshes identify regions sterically and energetically favorable for hydrophobic, hydrogen bond donor and hydrogen bond acceptor groups, respectively. The proper placement of the Ile-Pro-Ile groups in respect to the pharmacophoric requirements of the pocket is highlighted with rings. Specifically, gray indicates hydrophobic regions, while red and blue indicate regions suitable to receive hydrogen bond acceptor and donor groups, respectively.