RESIDUE   Q3S     18
CONECT      N      3 CA   H2   H   
CONECT      CA     4 N    C    C02  HA  
CONECT      C      3 CA   O    OXT 
CONECT      O      1 C   
CONECT      C01    4 C02  H011 H013 H012
CONECT      C02    4 CA   C01  N2   H021
CONECT      N2     3 C02  H3   H4  
CONECT      OXT    2 C    HXT 
CONECT      H2     1 N   
CONECT      H      1 N   
CONECT      HA     1 CA  
CONECT      H011   1 C01 
CONECT      H013   1 C01 
CONECT      H012   1 C01 
CONECT      H021   1 C02 
CONECT      H3     1 N2  
CONECT      H4     1 N2  
CONECT      HXT    1 OXT 
END   
HET    Q3S             18
HETNAM     Q3S (2R,3S)-2,3-diaminobutanoic acid
FORMUL      Q3S    C4 H10 N2 O2