Interactions of iron-thiol-nitrosyl compounds with the phosphoroclastic system of Clostridium sporogenes

Abstract

Certain reagents, such as ascorbate or iron salts and thiols, enhance the bacteriostatic action of nitrite on foodspoilage bacteria. This may be due to the formation of nitric oxide and iron-thiol4trosyl ((Fe-S-NO]) complexes. The minimum concentrations of these reagents required to inhibit growth of Clostridium sporogenes were investigated. A mixture of nitrite (0.72 mM) with iron (1.44 mM) and cystehe (2.16 mM) was found to be extremely inhibitory when autoclaved and diluted into the culture medium. This mixture caused rapid cessation of growth and loss of cell viability at a final concentration corresponding to 40 pM-nitrite. If added to the initial culture medium, it prevented growth at 5 pM-nitrite. The mixture W~S more inhibitory, on the basis of the nitrite concentration used, than the 'Perigo factor', obtained by autoclaving nitrite in growth medium. [Fe-%NO] compounds of known chemical structure were tested to determine if they were responsible for this effect. Total inhibition of cell growth was observed with the tetranuclear clusters [Fe,S,(NO),] (Roussin's black salt), [Fe,S,(NO),] or [Fe,Se,(NO),], added at concentrations equivalent to 10 pM-nitrite, or with [Fe2(SMe),(NO),] (methyl ester of Roussin's red salt), equivalent to 200 pM-nitrite. The rate of hydrogen production in growing cell cultures was inhibited by [Fe,S,(NO),] at levels equivalent to 2.5 pM-nitrite. EPR spectra of the inhibited cells showed features with g-values of 2-03, characteristic of mononuclear iron-nitrosyl species, and, under nonreducing conditions, an unusual signal at g = 1-65. There was no correlation between growth inhibition and the g = 2.03 signal, though there was a better correlation between inhibition and the g = 1.65 signal. The direct effects of the compounds were tested on the iron-sulphur proteins of the phosphoroclastic system, namely ferredoxin, pyruvate-ferredoxin oxidoreductase and hydrogenase. EPR spectra and enzyme assays showed that these proteins were not destroyed by [Fe,S,(NO),], [Fe,S,(NO),], [Fe,(SMe),(NO),], [Fe(SPh),(NO),], or M2 (an autoclaved mixture of 66 mM-cystehe, 3.6 mM-FeSO, and 0.72 m~-NaN0,) at concentrations higher than those that caused total inhibition of cell growth. Inhibition of cells by [Fe-S-NO] compounds is unlikely to be due to interaction with the preformed enzymes. The possible formation of iron-nitrosyl complexes in tritro, and their inhibitory actions, are discussed.

Trichomonas vaginalis and trichomoniasis in the Republic of Korea

“…and Staphylococcus aureus (Buchanan and Solberg, 1972;O'Leary and Solberg, 1976). Moreover, the addition of sodium nitrite to a suspension of C. sporogenes resulted in the growth inhibition of clostridia and of the phosphoroclastic system, which consists of PFOR (pyruvate ferredoxin oxidoreductase), ferredoxin and hydrogenase (Payne et al, 1990). Hydrogenosomal pyruvate metabolism in trichomonads is strikingly similar to the bacterial system, as demonstrated by Clostridia sp.…”

Nitrosative stress induced cytotoxicity in Giardia intestinalis

“…In bacteria (Chen et al. 1992; Payne et al. 1990) and in the flagellates Tritrichomonas foetus (Lloyd et al.…”

“…Nitrosation reactions are known to be responsible for the toxicity of compounds such as NaNO 2 , sodium nitroprusside (Na 2 [Fe(CN) 5 NO]) and Roussin's black salt (RBS, NH 4 Fe 4 S 3 (NO) 7 ) (to bacteria [e.g. Clostridium sporogenes (Payne et al 1990) and protozoa e.g. Trichomonas vaginalis (Ryu and Lloyd 1995)].…”

In SituNitric Oxide (NO) Measurement by Modified Electrodes: NO Labilized by Photolysis of Metal Nitrosyl Complexes

“…These sensors and a spectively. ᭧ 1997 Academic Press commercial NO sensor have been used to determine the stoichiometry of nitric oxide formation from photochemical reactions of several metal nitrosyl complexes The chemistry of nitric oxide (NO) 2 is of considerable of biological interest, i.e., sodium nitroprusside (22) and current interest owing to its wide-ranging biochemical Roussin's red and black salts (23)(24)(25). activity (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)).…”