Mechanisms of H sub 2 S production from cysteine and cystine by microorganisms isolated from soil by selective enrichment
- Ohio State Univ., Wooster (USA)
Hydrogen sulfide (H{sub 2}S) is a major component of biogenic gaseous sulfur emissions from terrestrial environments. However, little is known concerning the pathways for H{sub 2}S production from the likely substrates, cysteine and cystine. A mixed microbial culture obtained from Cystine-enriched soils was used in assays (50 min, 37C) with 0.05 M Tris-HCI (pH 8.5), 25 {mu}mol of L-cysteine, 25 {mu}mol of L-cystine, and 0.04 {mu}mol of pyridoxal 5 feet-phosphate. Sulfide and total pyruvate production were 17.6 and 17.2 nmol mg of protein{sup {minus}1} min{sup {minus}1}, respectively. Dithiothreitol did not alter reaction stoichiometry or the amount of H{sub 2}S and total pyruvate, whereas N-ethylmaleimide reduced both H{sub 2}S and total pyruvate production in the assay and by 15% with the addition of propargylglycine, a specific suicide inhibitor of cystathionine {gamma}-lyase. These data indicate that the substrate for the reaction was cysteine and the enzyme responsible for H{sub 2}S and pyruvate production was cysteine desulfhydrase. The enzyme had a K{sub m} of 1.32 mM and was inactivated by temperatures greater that 60C. Because cysteine is present in soil and cysteine desulfhydrase is an inducible enzyme, the potential for H{sub 2}S production by this mechanism exists in terrestrial environments.
- OSTI ID:
- 5273892
- Journal Information:
- Applied and Environmental Microbiology; (United States), Vol. 57:5; ISSN 0099-2240
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROGEN SULFIDES
BIOSYNTHESIS
MICROORGANISMS
METABOLISM
CYSTEINE
CYSTINE
ENZYME INHIBITORS
LYASES
TEMPERATURE EFFECTS
AMINO ACIDS
CARBOXYLIC ACIDS
CHALCOGENIDES
DISULFIDES
ENZYMES
HYDROGEN COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
SULFIDES
SULFUR COMPOUNDS
SYNTHESIS
THIOLS
540210* - Environment
Terrestrial- Basic Studies- (1990-)