Effect of different salts and detergents on luciferin–luciferase luminescence of the enchytraeid Fridericia heliota

The study addresses the effect produced by different inorganic salts and detergents (SDS, Triton X-100, the Tween series) on the ATP-dependent bioluminescent reaction catalyzed by the luciferase of the new earthworm species Fridericia heliota (Annelida: Clitellata: Oligochaeta: Enchytraeidae). It has been shown that the effect of divalent metal salts on luminescence is determined by the action of cations. Three of them – Mg2+, Mn2+ and Ca2+ – can stimulate luciferase activity at concentrations varying within a wide range, and Mn2+ can act as a 100%-effective substitute for Mg2+ in F. heliota luminescence reaction in vitro. The inhibitory effect of monovalent metal salts on luminescence is largely determined by the action of the anion part of the molecule. The effectiveness of the inhibitory effect of anions increases in the following order: Cl - < CO 3 - 2 ∼ SO 3 - 2 ∼ Br - < SO 4 - 2 ∼ PO 4 - 3 < NO 3 - < I - ≪ Cr 2 O 7 - 2 ≪ Fe ( CN ) 6 - 3 . Of the sodium salts, dodecyl sulfate, which is an anionic detergent, produces the strongest inhibitory effect on luciferase. On the contrary, nonionic detergents produce a stimulatory effect on the F. heliota luciferase. The action of the most effective of them – Triton X-100 – is determined by its ability to reduce the actual concentration of lipid inhibitors in the reaction mixture.