Inhibition of Leishmania major pteridine reductase by 2,4,6- triaminoquinazoline: Structure of the NADPH ternary complex

Abstract

The structure of Leishmania major pteridine reductase (PTR1) in complex with NADPH and the inhibitor 2,4,6-triaminoquinazoline (TAQ) has been solved in a new crystal form by molecular replacement and refined to 2.6 Å resolution. The inhibitor mimics a fragment, the pterin head group, of the archetypal antifolate drug methotrexate (MTX) and exploits similar chemical features to bind in the PTR1 active site. Despite being a much smaller molecule, TAQ displays a similar inhibition constant to that of MTX. PTR1 is a target for the development of improved therapies for infections caused by trypanosomatid parasites and this analysis provides information to assist the structure-based development of novel enzyme inhibitors. © 2004 International Union of Crystallography.