Analytical Sciences

Inhibition of Electrochemically Controlled Bioluminescence of Bacterial Luciferase by n-Alkyl Alcohols

Shinya YAMASAKI,* Shuto YAMADA,** and Kô TAKEHARA*

*Department of Chemistry, Faculty of Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan
**Center for Research and Advancement in Higher Education, Kyushu University, 744 Motooka, Fukuoka 819-0395, Japan

An electrochemical system has been developed in order to assay the effect of hydrophobic molecules on the bioluminescence of bacterial luciferase (BL). The inhibition of BL luminescence by the long-chain n-alkyl alcohol has been examined using this system. The 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol and 1-dodecanol inhibited the BL reaction in a dose-dependent manner. The IC₅₀ value, that is, the inhibitor concentration required to decrease the luminescence intensity by half, of these alcohols decreased with increasing the alkyl chain-length of the alcohols. In contrast, the shorter chain 1-hexanol did not inhibit the BL luminescence at all in the examined concentration range. These results indicate that the molecular size and hydrophobicity of the n-alkyl alcohol are the key factors to the inhibitory potency of the BL reaction. The IC₅₀ values are in agreement with values obtained for the bioluminescence of the firefly luciferase system. The proposed electrochemical BL luminescence system will be used for an inhibitory assay of hydrophobic drugs, such as general anesthetics on protein functions.

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