Cytochemical assay for phosphodiesterase I - help!

Peter Barling p.barling at
Fri Dec 15 19:07:47 EST 1995

We are attempting to assess the distribution of phosphodiesterase I 
on mammalian cells, histochemically.  So far, we have used thymidine 5' 
monophosphate alpha-naphthol ester as substrate, coupling the product 
(alpha-naphthol) to the diazo salt Fast Red TR, added at the same 
time as the substrate.  We have generally used an incubation pH of 10.0.

The resulting coupled dye product can be identified successfully, but 
the staining is rather faint.  Does anyone know of a better substrate 
or procedure?  Potentially, a method based on the use of the alternative
substrates thymidine 5' monophosphate AS-MX or bis(alpha-naphthyl) 
phosphate might give a better result.  Has anyone tried these substrates, 
or does anyone know of a source of commercial supplies of them?

If you have successful experience at detecting phosphodiesterase I 
histologically, we would love to hear from you, preferably by email 
(addressed, please to p.barling at

More information about the Cellbiol mailing list