Figure 3
From: The Rational Design of Therapeutic Peptides for Aminopeptidase N using a Substrate-Based Approach
Crystal structures of pAPN complexed with free amino acids. (A) The amino acid-binding pocket in pAPN. Left: the overall structure of pAPN complexed with methionine (in green). Right: an enlarged view of the amino acid-binding pocket in the pAPN body domain. The orientation of the view on the right is derived by rotating the view on the left 90° clockwise along a vertical axis. (B) Crystal structures of pAPN complexed with amino acids that are favored (Ala, Met, Arg and Leu) and disfavored (Ile and Asp) P1 residues for APN. pAPN residues are in magenta, and amino acids are in green. The catalytically critical hydrogen bond between the carbonyl oxygen of Ala348 and the C-terminal carboxyl group of amino acids is shown as a red dashed line in the structure with Ala, but is omitted in other panels for clarity. The interactions between the carbonyl oxygen of Ala348 and amino acid side chains are shown as black dashed lines. The distance between the carbonyl oxygen of Ala348 and the nearest atom on amino acid side chains is shown as a bidirectional arrow.
