RESIDUE 4FO 18 CONECT N 3 CA H H2 CONECT CA 4 N C CB HA CONECT C 3 CA O OXT CONECT O 1 C CONECT CB 4 CA CG HB2 HB3 CONECT CG 4 CB NZ HG3 HG2 CONECT NZ 3 CG HZ3 HZ2 CONECT OXT 2 C HXT CONECT H 1 N CONECT H2 1 N CONECT HA 1 CA CONECT HB2 1 CB CONECT HB3 1 CB CONECT HG3 1 CG CONECT HG2 1 CG CONECT HZ3 1 NZ CONECT HZ2 1 NZ CONECT HXT 1 OXT END HET 4FO 18 HETNAM 4FO (2R)-2,4-diaminobutanoic acid FORMUL 4FO C4 H10 N2 O2