RESIDUE 1AB 20 CONECT O4 2 C4 HO4 CONECT C4 4 O4 C3 C5 H4 CONECT C3 4 C4 O3 C2 H3 CONECT O3 2 C3 HO3 CONECT C2 4 C3 N1 H21 H22 CONECT N1 3 C2 C5 HN1 CONECT C5 4 C4 N1 C6 H5 CONECT C6 4 C5 O6 H61 H62 CONECT O6 2 C6 HO6 CONECT HO4 1 O4 CONECT H4 1 C4 CONECT H3 1 C3 CONECT HO3 1 O3 CONECT H21 1 C2 CONECT H22 1 C2 CONECT HN1 1 N1 CONECT H5 1 C5 CONECT H61 1 C6 CONECT H62 1 C6 CONECT HO6 1 O6 END HET 1AB 20 HETNAM 1AB 1,4-DIDEOXY-1,4-IMINO-D-ARABINITOL FORMUL 1AB C5 H11 N1 O3