Cyclic Nucleotide Phosphodiesterase: High Activity in a Mammalian Photoreceptor

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Science  18 Feb 1972:
Vol. 175, Issue 4023, pp. 757-758
DOI: 10.1126/science.175.4023.757


Purified outer segments of bovine rods exhibit phosphodiesterase activity against adenosine and guanosine cyclic 3',5'-monophosphates (cyclic AMP and cyclic GMP). The enzyme hydrolyzed cyclic GMP more rapidly than cyclic AMP at low substrate concentrations. The presence of high phosphodiesterase activity in this highly specialized organelle suggests that this enzyme may function in control of cyclic nucleotide concentration during visual excitation or adaptation.