Enzymes
| UniProtKB help_outline | 3,679 proteins |
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Reaction participants Show >> << Hide
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Namehelp_outline
[thioredoxin]-disulfide
Identifier
RHEA-COMP:10700
Reactive part
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- Name help_outline L-cystine residue Identifier CHEBI:50058 Charge 0 Formula C6H8N2O2S2 Positionhelp_outline n/n+3 SMILEShelp_outline C([C@@H](N*)CSSC[C@@H](C(=O)*)N*)(=O)* 2D coordinates Mol file for the small molecule Search links Involved in 51 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline adenosine 3',5'-bisphosphate Identifier CHEBI:58343 Charge -4 Formula C10H11N5O10P2 InChIKeyhelp_outline WHTCPDAXWFLDIH-KQYNXXCUSA-J SMILEShelp_outline Nc1ncnc2n(cnc12)[C@@H]1O[C@H](COP([O-])([O-])=O)[C@@H](OP([O-])([O-])=O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 140 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,431 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline sulfite Identifier CHEBI:17359 (CAS: 14265-45-3) help_outline Charge -2 Formula O3S InChIKeyhelp_outline LSNNMFCWUKXFEE-UHFFFAOYSA-L SMILEShelp_outline [O-]S([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 60 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline 3'-phosphoadenylyl sulfate Identifier CHEBI:58339 Charge -4 Formula C10H11N5O13P2S InChIKeyhelp_outline GACDQMDRPRGCTN-KQYNXXCUSA-J SMILEShelp_outline Nc1ncnc2n(cnc12)[C@@H]1O[C@H](COP([O-])(=O)OS([O-])(=O)=O)[C@@H](OP([O-])([O-])=O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 106 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
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Namehelp_outline
[thioredoxin]-dithiol
Identifier
RHEA-COMP:10698
Reactive part
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- Name help_outline L-cysteine residue Identifier CHEBI:29950 Charge 0 Formula C3H5NOS Positionhelp_outline n SMILEShelp_outline C(=O)(*)[C@@H](N*)CS 2D coordinates Mol file for the small molecule Search links Involved in 127 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline L-cysteine residue Identifier CHEBI:29950 Charge 0 Formula C3H5NOS Positionhelp_outline n+3 SMILEShelp_outline C(=O)(*)[C@@H](N*)CS 2D coordinates Mol file for the small molecule Search links Involved in 127 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:11724 | RHEA:11725 | RHEA:11726 | RHEA:11727 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Reaction mechanism of thioredoxin: 3'-phospho-adenylylsulfate reductase investigated by site-directed mutagenesis.
Berendt U., Haverkamp T., Prior A., Schwenn J.D.
Properties of purified recombinant adenosine 3'-phosphate 5'-phosphosulfate (PAdoPS) reductase from Escherichia coli were investigated. The Michaelis constants for reduced thioredoxin and PAdoPS are 23 microM and 10 microM, respectively; the enzyme has a Vmax of 94-99 mumol min-1 mg-1 and a molecu ... >> More
Properties of purified recombinant adenosine 3'-phosphate 5'-phosphosulfate (PAdoPS) reductase from Escherichia coli were investigated. The Michaelis constants for reduced thioredoxin and PAdoPS are 23 microM and 10 microM, respectively; the enzyme has a Vmax of 94-99 mumol min-1 mg-1 and a molecular activity/catalytically active dimer of 95 s-1. Adenosine 3',5'-bisphosphate (PAdoP) inhibits competitively (Ki 4 microM) with respect to PAdoPS; adenosine 2',5'-bisphosphate and sulfite are not inhibitory. Alkylation by SH-group inhibitors irreversibly inactivates the enzyme. The structural gene (cysH) encodes for a small polypeptide with a single Cys residue located in a conserved cluster (KXECGI/LH) of amino acids. Involvement of the only Cys and of Tyr209 in the reduction of PAdoPS to sulfite was investigated by site-specific mutagenesis: cysH was mutated by single-strand-overlay extension PCR; the mutated genes were cloned in pBTac1 and expressed in E. coli RL 22 (delta cysHIJ). Homogenous Cys239Ser and Tyr209Phe mutant PAdoPS reductases were investigated for altered catalytic properties. Mutation of the single Cys reduced Vmax by a factor of 4.5 x 10(3) (Vmax = 0.02-0.013 mumol min-1 mg-1) with marginal effects on Km for PAdoPS (19 microM) and reduced thioredoxin (14 microM). Mutation of Tyr209 drastically affected saturation with thioredoxin (Km 1.5 microM) and decreased Vmax (0.22-0.25 mumol min-1 mg-1) in addition to a small increase in Km for PAdoPS (31 microM). Chromophores as prosthetic groups were absent from recombinant PAdoPS reductase. Difference absorption spectra between reduced and oxidized forms of wild-type and mutated proteins indicated that, in addition to Cys239 and Tyr209, an unidentified Trp (delta lambda max 292 nm) appears to be involved in the reduction. The data suggest a special ping-pong mechanism with PAdoPS reacting with the reduced enzyme isomer in a Theorell-Chance type mechanism. << Less