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The Activity of 2′,3′‐Cyclic Nucleotide 3′‐Phosphodiesterase in Rat Tissues
Author(s) -
Weissbarth Sulamith,
Maker Howard S.,
Raes Ingrid,
Brannan Timothy S.,
Lapin Evelyn P.,
Lehrer Gerard M.
Publication year - 1982
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.1471-4159.1982.tb12540.x
Subject(s) - enzyme , cyclic nucleotide , microsome , phosphodiesterase , spleen , biochemistry , enzyme assay , biology , nucleotide , myelin , substrate (aquarium) , cell , cyclic nucleotide phosphodiesterase , synaptosome , medicine , chemistry , central nervous system , endocrinology , membrane , gene , immunology , ecology
The activity of the myelin‐associated enzyme 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP) was measured in 14 rat tissues and in subcellular fractions of rat liver by a sensitive fluorometric method, using cyclic NADP as substrate. CNP activity in brain (339 μmol/h/mg protein) was fourfold that of the sciatic nerve. The activities in tissues outside the nervous system ranged from a low of 0.42 μmol/h/mg protein in the unwashed red blood cell to a high of 9.96 in the spleen. The activity was highest in tissues containing cells with membranes capable of undergoing transformation and elaboration (spleen and thymus) and low in those in which the cell membranes are morphologically stable (muscle and red cell). The enzyme was found in all major liver subtractions, with the highest activities in the microsomal and nuclear fractions. Despite the large difference in the maximal velocities of CNP in brain and liver, the affinity of the liver enzyme for the substrate ( k m ) was similar to that of brain enzyme. Brain CNP was stable over a 48‐h postmortem period.