Phenolphthalein monophosphate

In practice it is often more convenient to measure the release of a phenol from an aryl phosphomonoester. Standard serum phosphatase methods employ phenyl phosphate (188), p-nitrophenyl phosphate (189), phenolphthalein monophosphate (140), or thymolphthalein monophosphate (141) where the phenol released can be determined spectrophoto-metrically [only the Bodansky method (13) uses a Pi determination]. A number of fluorogenic substrates have been used for phosphatase studies, e.g., jS-naphthyl phosphate (30, 148), 4-methylumbelliferyl phosphate (143), and 3-O-methylfluorescein phosphate (144) The main advantage here is the much greater sensitivity of fluorescence as compared with spectrophotometric assays as little as 1 pmole of 4-methyl-umbelliferone can be detected in continuous assay. 

Fig. 3 Structures of chromogenic phosphatase substrates (a) Para-nitrophenyl phosphate (b) phenolphthalein monophosphate (c) thymolphthalein monophosphate...

Sparkers MC, Crist ML, Sparkes RS (1975) High sensitivity of phenolphthalein monophosphate in detecting acid phosphatase isoenzymes. Anal Biochem 64 316-318... 

Babson AL, Greeley SJ, Coleman CM et al (1966) Phenolphthalein monophosphate as a substrate for serum alkaline phosphatase. Clin Chem 12 482-490... 

Other chromogenic substrates can also be exploited, including phenolphthalein monophosphate, thymophthalein monophosphate, P glycerophosphate, and uridine phosphate. Fluorigenic substrates can also be used such as P-naphthyl phosphate, 4-methylumbelliferyl phosphate, and 3-o-methylfluorescein monophosphate (21). 

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