Influence of Hydration Degree of Aerosol OT Reversed Micelles in Heptane on Inhibitory Effect of Gallic Acid Polydisulfide in Peroxidase-Dependent Oxidation of 3,3´,5,5´-Tetramethylbenzidine

E. I. Karasyova and D. I. Metelitza^*

Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, ul. Zhodinskaya 5/2, Minsk, 220141 Belarus; fax: (0172) 63-7274; E-mail: ibochbel@ns.igs.ac.by

^* To whom correspondence should be addressed.

Received November 20, 1997; Revision received March 25, 1998

---

Gallic acid polydisulfide (GAPD) inhibits with high efficiency tetramethylbenzidine (TMB) peroxidation at 20°C in reversed aerosol OT (AOT) micelles in heptane with various hydration degrees w₀ ranging from 8.3 to 47.2. Like in aqueous medium, the inhibition constant K_i for GAPD is ~10^-6 M and decreases with increasing w₀ from 15.3 to 25. In AOT micelles with various hydration degree, the initial rates of TMB oxidation catalyzed by peroxidase were determined in the absence of GAPD (v₀). Using the dependencies of the induction time of TMB peroxidation on the initial GAPD concentration, the values of the stoichiometric coefficient for inhibition by GAPD (f) were calculated at various hydration degrees of AOT micelles. Increase of hydration degree of AOT micelles is accompanied by a decrease of coefficient f from 30-31 (at low hydration degree) to 11.5-12.5 (at w₀ > 30), and this significantly exceeds the f values (2) typical for most known inhibitors.

---

KEY WORDS: gallic acid polydisulfide, peroxidase, tetramethylbenzidine, reversed micelles, aerosol OT, inhibitors of radical reactions, bioantioxidants, stoichiometric coefficient of inhibition, enzymes in non-aqueous media

---