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CYCLIC NUCLEOTIDE PHOSPHODIESTERASE OF THE BOVINE RETINA: ACTIVITY, SUBCELLULAR DISTRIBUTION AND KINETIC PARAMETERS
Author(s) -
Chader G.,
Johnson M.,
Fletcher R.,
Bensinger R.
Publication year - 1974
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1974.tb12183.x
Subject(s) - phosphodiesterase , hydrolysis , centrifugation , nucleotide , differential centrifugation , chemistry , cyclic nucleotide phosphodiesterase , biochemistry , enzyme , chromatography , cyclic nucleotide , atp hydrolysis , atpase , gene
— High phosphodiesterase activity for cyclic AMP and cyclic GMP was found in subcellular fractions of the bovine retina with more rapid hydrolysis of cyclic GMP than cyclic AMP in each fraction. Rod outer segments (ROS) and the supernatant fraction had highest activity. High enzyme activity remained associated with ROS membranes through several steps of purification by gradient centrifugation. A complex kinetic pattern was observed for cyclic AMP hydrolysis by the supernatant fraction yielding two values for K m ; a simple kinetic pattern was observed with cyclic GMP hydrolysis in supernatant and for both cyclic nucleotides in preparations of purified outer segments. Phosphodiesterase activity of outer segments was enhanced by Mg 2+ . Mn 2+ and inhibited by EDTA. Cyclic AMP had relatively little effect on the hydrolysis of cyclic GMP in supernatant or ROS while cyclic GMP inhibited hydrolysis of cyclic AMP in both fractions.