A CONVENIENT SPECTROPHOTOMETRIC ASSAY FOR PHOSPHODIESTERASES USING DINUCLEOSIDE-MONOPHOSPHATES AS SUBSTRATES

A coupled optical enzyme test for spleen and snake venom phosphodiesterase is described, that is based on the spectrophotometric determination of adenosine released from adenylyl‐(3′‐5′)‐adenosine, guanylyl‐(3′‐5′)‐adenosine and adenylyl‐(3′‐5′)‐guanosine. The liberation of adenosine from the dinucleoside monophosphates used as substrates is followed from the decrease in absorbance at 265 mμ, after addition of an excess of adenosine deaminase. The method proposed allows the detection of the specificity of a phosphodiesterase, i. e. whether a 3′‐mononucleotide or a 5′‐mononucleotide is released, since adenosine is liberated from GpA only by 3′‐mononucleotides producing phosphodiesterases, and from ApG only by 5′‐mononucleotides producing phosphodiesterases. Copyright © 1969, Wiley Blackwell. All rights reserved