Detergent inhibition of nitric-oxide reductase activity

Abstract

Gas chromatography revealed that exposure of extracts of the denitrifiers ‘Achromobacter cycloclastes’, Paracoccus denitrificans, Pseudomonas aeruginosa and Pseudomonas perfectomarina to Triton X-100 inhibited reduction of NO to N 2O, and thus concomitantly inhibited reduction of NO 2 − to N 2O. After exposure of extracts to Triton X-100, the ratio of H + consumed to NO 2 − added decreased from approx. 2.0 (for untreated extracts) to approx. 1.5, which indicated that NO 2 − was reduced to NO by the treated extracts. Addition of a CHAPS-soluble extracts (devoid of nitrite reductase activity but rich in nitric-oxide reductase activity) to the Triton X-100-treated extract of P. denitrificans restored capacity for reduction of NO 2 − on to N 2O. Exposure to either the NO that accumulated from reduction of NO 2 − or to enthetic NO transiently inhibited rates of NO 2 − reduction in Triton X-100-treated extracts. Use of an Oxides of Nitrogen analyzer indicated that only 5–33% of NO 2 − reduced by untreated extracts appeared in the stripping gas as NO, whereas 80–95% of NO 2 − reduced by Triton X-100-treated extracts was recovered as NO.