CRYSTAL STRUCTURE OF PTERIDINE REDUCTASE 1 (PTR1) FROM TRYPANOSOMA BRUCEI IN TERNARY COMPLEX WITH COFACTOR (NADP+) AND INHIBITOR 6,7-BIS(1-METHYLETHYL)PTERIDINE-2,4-DIAMINE (DX1) OXIDOREDUCTASE, PTERIDINE REDUCTASE, PTR1, TRYPANOSOMA BRUCEI, SHORT CHAIN DEHYDROGENASE, INHIBITOR 3JQ6