The substrate compound 3 in which {HEAD ~ the one or more non proteinaceous fluorescent moiety} comprises {TAIL ~ a dye} selected from a xanthene dye, a rhodamine dye, a fluorescein dye, a cyanine dye, a phthalocyanine dye, a squaraine dye and a bodipy dye 
comprises
The substrate compound 3 in which { HEAD ~ the one or more non proteinaceous fluorescent moiety } comprises { TAIL ~ a dye } selected from a xanthene dye , a rhodamine dye , a fluorescein dye , a cyanine dye , a phthalocyanine dye , a squaraine dye and a bodipy dye
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH