The effect of L-lysine alpha-oxidase from Trichoderma cf. aureoviride Rifai VKM F-4268D on the rat pheochromocytoma PC12 cell line

L-Amino acid oxidases (L-AAO; EC 1.4.3.2) comprise a group of flavoproteins that catalyze oxidative deamination of L-alpha amino acids to corresponding alpha-keto acids, NH₃ and H₂O₂. Most of these enzymes are homodimers with molecular mass of 100–150 kDa that exhibit antiviral, antifungal, antibacterial, and anticancer activity. Among this group of enzymes L-lysine alpha-oxidase (LO) is especially important as its biological effects may differ from the effects of other L-AAO, because this enzyme preferentially oxidizes L-lysine, the essential amino acid for the human body, without any practical effect on other amino acids. Since molecular mechanisms of the cytotoxic action of LO still require better understanding, in this study we have investigated a possible mechanism of action of LO from Trichoderma cf. aureoviride Rifai VKMF-4268D. A rat pheochromocytoma PC12 cell culture was used as a model. Using flow cytometry a dose-dependent cell death induced by LO was shown. The increase in intracellular reactive oxygen species detected by the 2,7-dichlorodihydrofluorescein assay suggests that the oxidative pathway is one of mechanisms underlying the cytotoxic LO action; however, this does not rule out the involvement of other (previously demonstrated) mechanisms of LO effects on cell death.