Allosteric regulation of Ca2+-calmodulin-dependent phosphodiesterase activity from the bovine brain

The Ca2+-calmodulin-dependent interaction of phosphodiesterase with phenyl-Sepharose was demonstrated. BSA caused incomplete competitive inhibition of phosphodiesterase activation by calmodulin. The 17-fold increase of the constant for phosphodiesterase activation by calmodulin was accompanied by an...

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Bibliographic Details
Published inBiokhimiia (Moscow, Russia) Vol. 52; no. 8; p. 1344
Main Authors Bobruskin, I D, Shaĭkhin, S M, Muratova, M V, Baranova, L A, Severin, E S
Format Journal Article
LanguageRussian
Published Russia (Federation) 01.08.1987
Subjects
3',5'-Cyclic-AMP Phosphodiesterases - metabolism
Allosteric Regulation
Animals
Brain - enzymology
Calcium - metabolism
Calmodulin - metabolism
Cattle
Enzyme Activation
In Vitro Techniques
Kinetics
Phosphodiesterase Inhibitors
Serum Albumin, Bovine - metabolism
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Summary:The Ca2+-calmodulin-dependent interaction of phosphodiesterase with phenyl-Sepharose was demonstrated. BSA caused incomplete competitive inhibition of phosphodiesterase activation by calmodulin. The 17-fold increase of the constant for phosphodiesterase activation by calmodulin was accompanied by an insignificant rise in the maximum rate of cAMP hydrolysis; in this case the value of the inhibition constant amounted to Ki approximately 6 microM. In the absence of calmodulin saturating concentrations of BSA reduced the enzyme activity nearly 3-4-fold. The effect of BSA on phosphodiesterase was incompetitive with respect to cAMP (Ki approximately 1.4 microM). Both phenomena are characteristic of incompetitive binding of BSA to the enzyme with respect to cAMP and calmodulin. Gel filtration data reflect the changes in the enzyme molecular weight during its interaction with BSA. All the above reactions of the enzyme are reversible.
ISSN:0320-9725