Fluorescence detection of proteases with AFC, AMC and MNA peptides using isoelectric focusing.

The fluorescence detection of proteases is not only possible with MNA but also with AFC and AMC peptides which were used up till now only for biochemical protease investigations. The MNA method is more sensitive due to the coupling capability of MNA with NSA than the AMC and AFC procedure. In comparison with the simultaneous azo-dye method the fluorescence technique may be inferior as far as the sharpness of the bands is concerned. The fluorescence staining is superior, however, if proteinases have to be investigated that are inhibited by diazonium salts, or where interference of diazonium salts and activators or inhibitors occurs; finally, it is a simple procedure to elucidate the value of MNA, AFC and AMC peptides for one and the same protease. In the field of applied isoelectric focusing the azo-dye and fluorescence procedure are now used together by us to detect possible differences in protease isoenzyme patterns in normal and diseased human biopsies, e.g. from liver, kidney and small intestine.