involvement of nitric oxide in the inhibition of the phosphoroclastic system in Clostridium sporogenes by sodium nitrite

Microbiology Section, Leatherhead Food Research Association, Randalls Road, Leatherhead, Surrey KT22 7R Y, U.K. ABSTRACT The phosphoroclastic system was demonstrated in cell-free extracts of Clostridium sporogenes by the production of carbon dioxide, acetyl phosphate, ATP and reduced NAD in the presence of pyruvate. The kinetics of acetyl phosphate production and NAD reduction were investigated. The addition of sodium nitrite to a suspension of C. sporogenes in glucose medium resulted in a rapid decrease in intracellular ATP concentration which was accompanied by an accumulation of pyruvate in the medium. This accumulation of pyruvate was caused by inhibition of the phosphoroclastic system by nitrite. Nitrite inhibits this system by reaction of nitric oxide, formed from nitrite, with the non-haem iron of pyruvate: ferredoxin oxidoreductase.