Abstract
The central protein of the sulfur-oxidizing enzyme system of Paracoccus pantotrophus, SoxYZ, reacts with three different Sox proteins. Its active site Cys110(Y) is on the carboxy-terminus of the SoxY subunit. SoxYZ "as isolated" consisted mainly of the catalytically inactive SoxY-Y(Z)(2) heterotetramer linked by a Cys110(Y)-Cys110(Y) interprotein disulfide. Sulfide activated SoxYZ "as isolated" 456-fold, reduced the disulfide, and yielded an active SoxYZ heterodimer. The reductant tris(2-carboxyethyl)phosphine (TCEP) inactivated SoxYZ. This form was not re-activated by sulfide, which identified it as a different inactive form. In analytical gel filtration, the elution of "TCEP-treated" SoxYZ was retarded compared to active SoxYZ, indicating a conformational change. The possible enzymes involved in the re-activation of each inactive form of SoxYZ are discussed.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / antagonists & inhibitors
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Bacterial Proteins / chemistry*
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Bacterial Proteins / isolation & purification
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Catalysis
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Enzyme Inhibitors / pharmacology
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Isoenzymes / antagonists & inhibitors
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Isoenzymes / chemistry
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Isoenzymes / isolation & purification
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Models, Molecular
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Oxidoreductases Acting on Sulfur Group Donors / antagonists & inhibitors
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Oxidoreductases Acting on Sulfur Group Donors / chemistry*
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Oxidoreductases Acting on Sulfur Group Donors / isolation & purification
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Paracoccus pantotrophus / enzymology*
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Phosphines / pharmacology
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Protein Subunits / chemistry
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Protein Subunits / isolation & purification
Substances
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Bacterial Proteins
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Enzyme Inhibitors
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Isoenzymes
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Phosphines
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Protein Subunits
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tris(2-carboxyethyl)phosphine
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Oxidoreductases Acting on Sulfur Group Donors
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SoxZ protein, Paracoccus pantotrophus