RESIDUE EPO 11 CONECT O1 1 C1 CONECT C1 2 O1 C2 CONECT C2 4 C1 C3 O2 H2 CONECT O2 2 C2 HO2 CONECT C3 4 C2 C4 1H3 2H3 CONECT C4 2 C3 O4 CONECT O4 1 C4 CONECT H2 1 C2 CONECT 1H3 1 C3 CONECT 2H3 1 C3 CONECT HO2 1 O2 END HET EPO 11 HETNAM EPO 1-OXO-(2-HYDROXYBUTYL)-4-OXO GROUP FORMUL EPO C4 H4 O3