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Polymyxin B Is a Selective and Potent Antagonist of Calmodulin

Polymyxin B Is a Selective and Potent Antagonist of Calmodulin

L Hegemann, L A van Rooijen, J Traber, B H Schmidt

Eur J Pharmacol. 1991 May 25;207(1):17-22.

PMID: 1915592

Abstract:

Polymyxin B, a cyclic peptide antibiotic, is considered to be a rather selective antagonist of protein kinase C. This drug is therefore widely used to evaluate the involvement of protein kinase C in cellular processes. In the present study, we investigated the effects of polymyxin B on the activity of calmodulin-dependent cyclic 3':5'-nucleotide phosphodiesterase in vitro. The drug potently inhibited this enzyme (IC50 80 nM in the presence of 500 microM Ca2+), while about 200-fold higher concentrations were required to inhibit protein kinase C to the same extent. Phosphodiesterase inhibition was competitive with respect to Ca2+ and calmodulin. Evidence for the formation of a complex between polymyxin B and calmodulin was obtained by polyacrylamide gel electrophoresis under non-denaturing conditions, and by affinity chromatography of calmodulin on polymyxin B-agarose. We therefore suggest that, at least in vitro, polymyxin B is a potent and selective inhibitor of calmodulin.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR42411071	Polymyxin B-Agarose			Price

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