Removal of the alanine side chain to create the A108G binding pocket (Fig. ) likely creates a 'looser' fit for 5 and 3. Thus, it is reasonable to conclude that the contrasting behaviour of 5 and 3 stems from differences in the bond lengths and geometry of the oxazole that pose the CO2H group differently for each molecule in the binding pocket. Additionally, the position of the electronwithdrawing CO2H may alter the efficiency of emissive pathways once bound.