Novel chromogenic and/or fluorogenic substrates for monitoring catalytic or enzymatic activity

A substrate at least essentially stable towards medium-induced hydrolysis of the phosphate ester at the 3'-position and having the following structural formula:

• ##STR10## wherein B is a nucleotide base capable of assisting, after deblocking of the substrate, in hydrolysis of the phosphate ester at the 3'-position, R is a moiety selected from the group consisting of umbelliferonyl, 4-methyl umbelliferonyl, 3-flavonyl, o-nitrophenyl, m-nitrophenyl, p-nitrophenyl, dinitrophenyl, cyanophenyl, acylphenyl, carboxyphenyl, phenylsulfonate, phenylsulfonyl and phenylsulfoxide, R' is a moiety selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, araalkyl, acyl, oxaalkyl and oxacycloalkyl, and R" is hydrogen or a cation selected from the group consisting of calcium, barium, lithium, sodium, ammonium, substituted ammonium and pyridinium and R'" is a blocking group capable of at least essentially preventing medium-induced hydrolysis of the phosphate ester at the 3' position, R'" being capable of being removed to provide a substrate characterized by the ability to undergo catalytic induced hydrolysis of the phosphate ester at the 3' position to yield a species capable of being monitored spectrophotometrically or fluorometrically.