3JQB CRYSTAL STRUCTURE OF PTERIDINE REDUCTASE 1 (PTR1) FROM TRYPANOSOMA BRUCEI IN TERNARY COMPLEX WITH COFACTOR (NADP+) AND INHIBITOR 2-AMINO-5-(2-PHENYLETHYL)-3,7-DIHYDRO-4H- PYRROLO[2,3-D]PYRIMIDIN-4-ONE (DX6) OXIDOREDUCTASE, PTERIDINE REDUCTASE, PTR1, TRYPANOSOMA BRUCEI, SHORT CHAIN DEHYDROGENASE, INHIBITOR