Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Although >10
μM hydrogen sulfide typically is toxic to eukaryotic cells, <1
μM sulfide is rapidly consumed and oxidized. To measure sulfide consumption in such low concentrations, we built a “Sulfidostat.” The apparatus uses a sulfide-specific electrode to measure the concentration of free sulfide. The electrode is connected to a computer that controls a syringe pump. The pump injects Na
2S solution into the sample chamber to maintain a constant concentration. Since the response of the electrode to low sulfide concentrations at neutral pH had not been previously validated, that was measured. Then using the Sulfidostat, the rate of sulfide consumption is the rate at which it is pumped into the sample to maintain a constant concentration. The protozoan
Tetrahymena pyriformis was used to demonstrate the apparatus; maximum sulfide consumption occurred near 0.5
μM sulfide at a rate of 250
nmol (g protein)
−1 s
−1. That is higher than the rate calculated from the disappearance of sulfide following a bolus addition, a difference that can be explained by the slow response of the electrode and by reversible binding of sulfide by the cells. The Sulfidostat can measure sulfide consumption at concentrations lower than previously have been possible.