Abstract
OPINION article Front. Physiol., 18 April 2012Sec. Membrane Physiology and Membrane Biophysics https://doi.org/10.3389/fphys.2012.00101
Highlights
Previous studies report measurement of endogenous concentrations of sulfide by methods involving high concentrations of acids; contamination by free H2S released from acid-labile sulfur resulted in an overestimate of the free H2S levels (50– 160 μM; Goodwin et al, 1989; Warenycia et al, 1989; Savage and Gould, 1990)
CBS and cystathionine γ-lyase (CSE) metabolize cysteine and/ or homocysteine to release H2S, whereas 3-mercaptopyruvate sulfurtransferase (3MST) produces H2S from 3-mercaptopyruvate (3MP), which is produced by the action of cysteine aminotransferase (CAT) on cysteine and α-ketoglutarate (Cooper, 1983; Shibuya et al, 2009a,b). 3MST requires cofactors to reduce a persulfide intermediate generated between a cysteine residue of 3MST and a sulfide provided by 3MP
We recently found that thioredoxin and dihydrolipoic acid (DHLA) are endogenous reducing cofactors that facilitate H2S release from 3MST (Mikami et al, 2011a)
Summary
Previous studies report measurement of endogenous concentrations of sulfide by methods involving high concentrations of acids; contamination by free H2S released from acid-labile sulfur resulted in an overestimate of the free H2S levels (50– 160 μM; Goodwin et al, 1989; Warenycia et al, 1989; Savage and Gould, 1990). A sulfur/silver electrode has frequently been used for the measurement of sulfide concentrations in biological samples. The electrode measures the level of S2−, and a pKa value of 13.9 results in the replacement of cysteine sulfide groups in proteins with hydroxyl groups, thereby releasing H2S from proteins.
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