The application of two-dimensional fluorescence spectroscopy for the on-line evaluation of modified enzymatic enantioselectivities in organic solvents by forming substrate salts

We recently developed a pseudo-enantiomeric reaction which was monitored on-line via 2D-fluorescence spectroscopy in different reaction media. During enzymatic reactions, conclusions about the converted substrates and the enantioselectivity could be drawn immediately, using two different fluorescence spectroscopic detectable substrates, l-phenylalanine-7-amido-4-methylcoumarine and d-phenylalanine-7-amido-4-trifluoromethylcoumarine. Now, due to the enlargement of one of the coumarin substrates via salt formation, it was possible to influence the enzymatyic enantioselectivity in toluene and to monitor the impact of the bulky counterion on-line.