We selected peptides from GAPDH for LiP to assess structural changes after propachlor treatment. We found several GAPDH peptides to be more proteolytically sensitive to proteinase K after propachlor treatment (Figure and Figure ), including the active site peptides LVINGNPITIFQER, LISWYDNEFGYSNR, VGVNGFGR. Hence, propachlor induces a more extended conformation in GAPDH, consistent with destabilization. Destabilization of GAPDH could also affect proteinprotein interactions. One of the destabilized peptides, VPTANVSVVDLTCR, is involved in the dimer interface of GAPDH 108 . Mutations in this peptide are associated with conformational changes at the dimeric interface and a loss of tetrameric stability .