title: C4H9NO2S
text: # C4H9NO2S
  
  The molecular formula $C_4H_9NO_2S$ may refer to:
  
  * Homocysteine, a non-proteinogenic α-amino acid
  * S-Methylcysteine, amino acid with the nominal formula $CH_3SCH_2CH(NH_2)CO_2H;$ the S-methylated derivative of cysteine
  