Probing the KRas Switch II Groove by Fluorine NMR Spectroscopy

While there has been recent success in the development of KRasG12C inhibitors, unmet needs for selective inhibitors and tool compounds targeting the remaining oncogenic KRas proteins remain. Here, we applied trifluoromethyl-containing ligands of KRas proteins as competitive probe ligands to assay the occupancy of the switch II pocket by 19F NMR spectroscopy. Structure-activity-relationship studies of probe ligands increased the sensitivity of the assay and identified structures that differentially detected each nucleotide state of KRasG12D. These differences in selectivity, combined with the high resolution of 19F NMR spectroscopy, enabled this method to be expanded to assay both nucleotide states of the protein simultaneously. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/500267v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@2fe99corg.highwire.dtl.DTLVardef@19223bdorg.highwire.dtl.DTLVardef@1686090org.highwire.dtl.DTLVardef@19b9d05_HPS_FORMAT_FIGEXP M_FIG C_FIG