L. P. Kuznetsova, V. A. Samokish, E. E. Sochilina

Sechenov Institute of Evolutionary Physiology and Biochemistry,
Russian Academy of Sciences, St. Petersburg, Russia;
е-mail: esoch@iephb.ru

The influence of cationic detergent cetyltrimethylammonium on the human blood cholinesterases activity (erythrocyte acetylcholinesterase and plasma butyrylcholinesterase) in reactions of hydrolysis of α-thionaphthylacetat and acetylthiocholine is studied. It is shown, that cetyltrimethylammonium is reversible effectоr for both cholinesterases. This compound competitively inhibited enzymatic hydrolysis of acetylthiocholine by both cholinesterases, and in the reactions of enzymatic hydrolysis α-thionaphthylacetat display as the synergistic activator – in experiments with butyrylcholinesterase, and as the reversible inhibitor – in experiments with acetylcholinesterase. Kinetic constants in reaction of acetylcholinesterase inhibition by cetyltrimethylammonium defined by means of different substrates – α-thionaphthylacetat and acetylthiocholin. They are close among themselves and amount (2.5 ± 0.3)×10^-5 and (2.8 ± 0.3)×10^-5 М, accordingly. Butyrylcholinesterase was more sensitive to influence of cetyltrimethylammonium. The kinetic constants defined for this enzyme by the effect of inhibition of acetylthiocholin hydrolysis or activation of α-thionaphthylatcetat hydrolysis, are also close among themselves and amount (3.9 ± 0.4)×10^-6 and (4.4 ± 0.4)×10^-6 М, accordin­gly.