ALDEHYDE DEHYDROGENASE AND CYTOTOXICITY OF PURIFIED BOVINE SERUM AMINE OXIDASE AND SPERMINE IN CHINESE-HAMSTER OVARY CELLS

Bovine serum amine oxidase (EC 1.4.3.6) catalyses the oxidative deamin ation of polyamines giving rise to the corresponding aldehydes, ammoni a, and hydrogen peroxide. It has been suggested that the dialdehyde pr oduced during the oxidation of spermine subsequently undergoes spontan eous beta-elimination to form acrolein. Oxidation of the aldehydes by aldehyde dehydrogenase (EC 1.2.1.5) thus eliminates these reactive spe cies and prevents the formation of acrolein. This work studies the rol e of each of the oxidation products of spermine in cytotoxicity induce d by purified bovine serum amine oxidase. The inhibition patterns of N AD-dependent aldehyde dehydrogenase and catalase against cytotoxicity of bovine serum amine oxidase were determined in Chinese hamster ovary cells at 37 degrees C. Cytotoxicity caused by exogenous hydrogen pero xide, added directly (> 10 mu M) or generated by glucose oxidase (0.5 U/mL), was completely inhibited by catalase. Cytotoxicity caused by bo vine serum amine oxidase (5.7 x 10(-3) U/mL) and spermine (340 mu M) w as completely inhibited by catalase only during short incubation times after which time cytotoxicity occurred. This indicates that hydrogen peroxide was the only species contributing to cytotoxicity at this sta ge of the reaction. Aldehyde dehydrogenase alone caused partial inhibi tion of cytotoxicity, but only later in the reaction. Cytotoxicity was completely eliminated in the presence of both catalase and aldehyde d ehydrogenase. Exogenous acrolein (> 50 mu M) also caused cytotoxicity in Chinese hamster ovary cells. However, hydrogen peroxide was toxic t o cells at lower concentrations and at shorter exposure times relative to aldehydes. These data show that both peroxide and aldehydes contri bute to cytotoxicity of oxidation products of spermine. Aldehydes such as acrolein are responsible for cytotoxicity that cannot be accounted for by hydrogen peroxide.