Inhibition mechanism of flavin by deprenyl as an acetylenic irreversible inhibitor

Abstract.

Possible inhibition mechanisms of flavin (isoalloxazine) with (−)-deprenyl as an acetylenic irreversible inhibitor have been investigated in detail by ab initio methods with the 6-31G* basis set through the simplified model compounds 3-formyl-2-imino-1-hydropyrazine and propargylamine. The resulting compounds have been verified by calculations with the 3-21G basis set using flavin itself and the model of (−)-deprenyl for confirmation of the reactions through the simplified models. Two cyclic O4,N5- and C4a,N5-covalent adducts have been found. The latter was the most stable and was considered to be the final irreversible product. The intermediates in the reaction, the acyclic C4a- or N5-allenic compounds and their hydrogen-transferred cyanine-type compounds, are in agreement with the results of experimental photochemical reactions. In most of the reaction processes, hydrogen migration played an important role.