Elemental sulfur: Toxicityin vivoandin vitroto bacterial luciferase,in vitroyeast alcohol dehydrogenase, and bovine liver catalase

Abstract

The aim of this research was to analyze the effects and the modes of action of elemental sulfur (S(0)) in bioluminescence and respiration of Vibrio fischeri cells and the enzymes crude luciferase, pure catalase, and alcohol dehydrogenase (ADH). Metallic copper removed sulfur and reduced the toxicity of acetone extracts of sediment samples analyzed in the bioluminescence test. The sulfur inhibition of cell bioluminescence was noncompetitive with decanal, the luciferase substrate; reversible, with maximum toxicity after 15 min (EC(50) = 11.8 microg/L); and almost totally recovered after 2 h. In vitro preincubation of crude luciferase extract with sulfur (0.28 ppm) weakly inhibited bioluminescence at 5 min, but at 30 min the inhibition reached 60%. Increasing the concentration of sulfur in the parts per million concentration range in vitro decreased bioluminescence, which was not constant, but depended on exposure time, and no dead-end/total inhibition was observed. The redox state of enzymes in the in vitro system significantly affected inhibition. Hydrogen peroxide restored fully and the reducing agent dithiothreitol, itself toxic, restored only partially luciferase activity in the presence of sulfur. Sulfur (5.5 ppm) slightly inhibited ADH and catalase, and dithiothreitol enhanced sulfur inhibition. High sulfur concentrations (2.2 ppm) inhibited the bioluminescence and enhanced the respiration rate of V. fischeri cells. Elemental sulfur data were interpreted to show that sulfur acted on at least a few V. fischeri cell sites: reversibly modifying luciferase at sites sensitive to/protected by oxidative and reducing agents and by affecting electron transport processes, resulting in enhanced oxygen consumption. Sulfur together with an enzyme reducing agent inhibited the oxidoreductive enzymes ADH and catalase, which have --SH groups, metal ion cofactors, or heme, respectively, in their active centers.

Reduced sulfur species in a stratified seawater lake (Rogoznica Lake, Croatia); seasonal variations and argument for organic carriers of reactive sulfur

“…6). Elemental sulfur, S 8 , is capable of disrupting enzyme function (Cetkauskaite et al, 2004). Therefore, it would be possible that S 8 was the actual toxic agent in the upper water column in October 1997.…”

Gandhak (Sulphur) a Conceptual Study

“…Large doses may have hepatotoxic properties. Rarerly sulphide absorbed from the intestine may produce the enterogenous cyanosis due to the formation of sulphaemoglobin [34][35] .…”

Environmental and Synthetic Sulphydryl Group Inhibitors: Effects on Bioluminescence and Respiration in Vibrio fischeri

“…against the toxicity of S 0 in vivo by an excess of the substrate, decanal (which is known to bind in the hydrophobic region of luciferase [13,17]); and 3) that the redox state of the enzyme in vitro (low concentrations of hydrogen peroxide and 2,4dithio-DL-threitol [DTT]) reversed the toxic effects of S 0 (16). It was deduced that S 0 acted as a reversible modifier, rather than an inhibitor, in V. fischeri cells, and did not compete with the natural substrate, decanal.…”

“…Data from previous research (16) on the mode of action of S 0 in V. fischeri in vivo and in vitro showed that: 1) the inhibition of bioluminescence by S 0 was reversible during exposures of up to 2 hours; 2) bioluminescence was not protected…”