INACTIVATION OF BACTERIAL RESPIRATORY-CHAIN ENZYMES BY SINGLET OXYGEN

To distinguish the bactericidal action of singlet oxygen (O-1(2)) from hypohalous acids, wild-type and lycopene transformant E. coli strains were exposed to each of the oxidants and then bacterial viability was investigated. 102 was generated by chemical and enzymatic systems at pH 4.5. Exposure of wildtype E. coli to 102 caused a significant loss of E, coli viability due to inactivation of membrane respiratory chain enzymes by O-1(2). This action of O-1(2) could be attenuated by lycop ene in the bacterial cell membrane. In the lycopene transformant strai n of E, coli, inactivation of NADH oxidase and succinate oxidase by hy pohalous acids were significantly suppressed, but E, coli viability wa s unaffected, Based on these findings, we suggest that phagocytic leuk ocytes produce O-1(2) as a major bactericidal oxidant in the phagosome . (C) 1998 Federation of European Biochemical Societies.