Studies on the soluble phosphodiesterases of chicken gizzard smooth muscle.
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ABSTRACT: In this study we describe the identification of four soluble forms of cyclic nucleotide phosphodiesterase from chicken gizzard smooth muscle. These isoenzymes were separated from one another by ion-exchange chromatography on DEAE-cellulose and by calmodulin-Sepharose affinity chromatography. Each form migrates as a single discrete band when it is electrophoresed on non-denaturing polyacrylamide gels and stained for phosphodiesterase activity. Each form is also eluted as a single peak on gel-permeation chromatography, giving apparent Mr values of 114 000, 116 000, 122 000 and 59 000. All four enzymes have apparent Km values in the 0-20 microM range, although their relative specificities for cyclic AMP and cyclic GMP differ. Two of the forms bind to calmodulin in a Ca2+-dependent manner; however, only one is activated by calmodulin. The interaction of the second calmodulin-binding form with calmodulin is disrupted by the papaverine derivative verapamil without significantly altering the hydrolytic activity of the enzyme.
SUBMITTER: Birnbaum RJ
PROVIDER: S-EPMC1152445 | biostudies-other | 1983 Dec
REPOSITORIES: biostudies-other
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