title: Studies on the soluble phosphodiesterases of chicken gizzard smooth muscle.
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.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002147:Calmodulin / Q000378:metabolism; D002645:Chickens; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D005895:Gizzard, Avian / Q000201:enzymology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D009130:Muscle, Smooth / Q000201:enzymology*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D012995:Solubility; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D007527:Isoenzymes; D010726:Phosphodiesterase Inhibitors; D014700:Verapamil; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015106:3',5'-Cyclic-GMP Phosphodiesterases