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Interaction of Flavonoids With Rabbit Muscle Phosphorylase Kinase

Interaction of Flavonoids With Rabbit Muscle Phosphorylase Kinase

S M Kyriakidis, T G Sotiroudis, A E Evangelopoulos

Biochim Biophys Acta. 1986 Jun 5;871(2):121-9.

PMID: 3085712

Abstract:

We have examined the effect of several flavonoids on the activity of phosphorylase kinase from rabbit skeletal muscle. From 14 flavonoids tested, the flavones quercetin and fisetin were found to be efficient inhibitors of nonactivated phosphorylase kinase when assayed at pH 8.2, causing 50% inhibition at a concentration of about 50 microM, while the flavanone hesperetin stimulated phosphorylase kinase activity about 2-fold when tested at 250 microM. The efficiency of quercetin in inhibiting the kinase is higher when the enzyme is stimulated either by ethanol or by alkaline pH. Both casein and troponin phosphorylation by phosphorylase kinase and the autophosphorylation of the kinase were inhibited by quercetin. In addition, quercetin was found to be a competitive inhibitor of ATP for the phosphorylation of phosphorylase b at pH 8.2. These observations suggest that the inhibitory effect of the flavone is directly on the phosphorylase kinase molecule. Trypsin-activated phosphorylase kinase was inhibited by quercetin and stimulated by hesperetin, as for the native enzyme.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP9032104	Phosphorylase a from rabbit muscle		9032-10-4	Price

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