Inhibition of Branched-Chain α-Ketoacid Dehydrogenase Kinase by Thiamine Pyrophosphate at Different Potassium Ionic Levels

Keiichi AKITA; Yukihiro FUJIMURA; Gustavo BAJOTTO; Yoshiharu SHIMOMURA

doi:10.1271/bbb.80749

Biochemistry & Molecular Biology Notes

Inhibition of Branched-Chain α-Ketoacid Dehydrogenase Kinase by Thiamine Pyrophosphate at Different Potassium Ionic Levels

Keiichi AKITA, Yukihiro FUJIMURA, Gustavo BAJOTTO, Yoshiharu SHIMOMURA

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Keywords: branched-chain α-ketoacid dehydrogenase kinase, thiamine pyrophosphate, enzyme inhibitor, IC₅₀, inhibition constant

JOURNAL FREE ACCESS

2009 Volume 73 Issue 5 Pages 1189-1191

DOI https://doi.org/10.1271/bbb.80749

View "Advance Publication" version (May 7, 2009).

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Abstract

Inhibition of branched-chain α-ketoacid dehydrogenase kinase (BDK) by thiamine pyrophosphate (TPP) was analyzed at two potassium ion (K⁺) concentrations. IC₅₀ values of 4.6 and 8.0 μM and inhibition constant values of 3.2 and 16.4 μM were obtained in the presence of 20 and 100 mM K⁺, respectively. These results suggest that BDK is less sensitive to TPP inhibition under physiological TPP and K⁺ concentrations.

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