OXIDOREDUCTASE, PTERIDINE REDUCTASE, PTR1, TRYPANOSOMA BRUCEI, SHORT CHAIN DEHYDROGENASE, INHIBITOR CRYSTAL STRUCTURE OF PTERIDINE REDUCTASE 1 (PTR1) FROM TRYPANOSOMA BRUCEI IN TERNARY COMPLEX WITH COFACTOR (NADP+) AND INHIBITOR 1,3,5-TRIAZINE-2,4,6-TRIAMINE (AX2) 3JQF