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Photochem Photobiol Sci. 2011 Jun;10(6):1039-45. doi: 10.1039/c0pp00379d. Epub 2011 Mar 15.

Kinetics of inhibition of firefly luciferase by dehydroluciferyl-coenzyme A, dehydroluciferin and L-luciferin.

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Centro de Investigação em Química (UP), Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Porto, Portugal.


The inhibition mechanisms of the firefly luciferase (Luc) by three of the most important inhibitors of the reactions catalysed by Luc, dehydroluciferyl-coenzyme A (L-CoA), dehydroluciferin (L) and L-luciferin (L-LH(2)) were investigated. Light production in the presence and absence of these inhibitors (0.5 to 2 μM) has been measured in 50 mM Hepes buffer (pH = 7.5), 10 nM Luc, 250 μM ATP and D-luciferin (D-LH(2), from 3.75 up to 120 μM). Nonlinear regression analysis with the appropriate kinetic models (Henri-Michaelis-Menten and William-Morrison equations) reveals that L-CoA is a non-competitive inhibitor of Luc (K(i) = 0.88 ± 0.03 μM), L is a tight-binding uncompetitive inhibitor (K(i) = 0.00490 ± 0.00009 μM) and L-LH(2) acts as a mixed-type non-competitive-uncompetitive inhibitor (K(i) = 0.68 ± 0.14 μM and αK(i) = 0.34 ± 0.16 μM). The K(m) values obtained for L-CoA, L and L-LH(2) were 16.1 ± 1.0, 16.6 ± 2.3 and 14.4 ± 0.96 μM, respectively. L and L-LH(2) are strong inhibitors of Luc, which may indicate an important role for these compounds in Luc characteristic flash profile. L-CoA K(i) supports the conclusion that CoA can stimulate the light emission reaction by provoking the formation of a weaker inhibitor.

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