Enzymes
UniProtKB help_outline | 3,581 proteins |
Enzyme class help_outline |
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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 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 9,176 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
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Namehelp_outline
reduced [2Fe-2S]-[ferredoxin]
Identifier
RHEA-COMP:10001
Reactive part
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- Name help_outline [2Fe-2S]1+ Identifier CHEBI:33738 Charge 1 Formula Fe2S2 InChIKeyhelp_outline MAGIRAZQQVQNKP-UHFFFAOYSA-N SMILEShelp_outline S1[Fe]S[Fe+]1 2D coordinates Mol file for the small molecule Search links Involved in 236 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 123 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 123 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
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Namehelp_outline
oxidized [2Fe-2S]-[ferredoxin]
Identifier
RHEA-COMP:10000
Reactive part
help_outline
- Name help_outline [2Fe-2S]2+ Identifier CHEBI:33737 Charge 2 Formula Fe2S2 InChIKeyhelp_outline XSOVBBGAMBLACL-UHFFFAOYSA-N SMILEShelp_outline S1[Fe+]S[Fe+]1 2D coordinates Mol file for the small molecule Search links Involved in 236 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:42336 | RHEA:42337 | RHEA:42338 | RHEA:42339 | |
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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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The function and properties of the iron-sulfur center in spinach ferredoxin: thioredoxin reductase: a new biological role for iron-sulfur clusters.
Staples C.R., Ameyibor E., Fu W., Gardet-Salvi L., Stritt-Etter A.L., Schurmann P., Knaff D.B., Johnson M.K.
Thioredoxin reduction in chloroplasts is catalyzed by a unique class of disulfide reductases which use a [2Fe-2S]2+/+ ferredoxin as the electron donor and contain an Fe-S cluster as the sole prosthetic group in addition to the active-site disulfide. The nature, properties, and function of the Fe-S ... >> More
Thioredoxin reduction in chloroplasts is catalyzed by a unique class of disulfide reductases which use a [2Fe-2S]2+/+ ferredoxin as the electron donor and contain an Fe-S cluster as the sole prosthetic group in addition to the active-site disulfide. The nature, properties, and function of the Fe-S cluster in spinach ferredoxin:thioredoxin reductase (FTR) have been investigated by the combination of UV/visible absorption, variable-temperature magnetic circular dichroism (MCD), EPR, and resonance Raman (RR) spectroscopies. The results indicate the presence of an S = 0 [4Fe-4S]2+ cluster with complete cysteinyl-S coordination that cannot be reduced at potentials down to -650 mV, but can be oxidized by ferricyanide to an S = 1/2 [4Fe-4S]3+ state (g = 2.09, 2.04, 2.02). The midpoint potential for the [4Fe-4S]3+/2+ couple is estimated to be +420 mV (versus NHE). These results argue against a role for the cluster in mediating electron transport from ferredoxin (Em = -420 mV) to the active-site disulfide (Em = -230 mV, n = 2). An alternative role for the cluster in stabilizing the one-electron-reduced intermediate is suggested by parallel spectroscopic studies of a modified form of the enzyme in which one of the cysteines of the active-site dithiol has been alkylated with N-ethylmaleimide (NEM). NEM-modified FTR is paramagnetic as prepared and exhibits a slow relaxing, S = 1/2 EPR signal, g = 2.11, 2.00, 1.98, that is observable without significant broadening up to 150 K. While the relaxation properties are characteristic of a radical species, MCD, RR, and absorption studies indicate at least partial cluster oxidation to the [4Fe-4S]3+ state. Dye-mediated EPR redox titrations indicate a midpoint potential of -210 mV for the one-electron reduction to a diamagnetic state. By analogy with the properties of the ferricyanide-oxidized [4Fe-4S] cluster in Azotobacter vinelandii 7Fe ferredoxin [Hu, Z., Jollie, D., Burgess, B. K., Stephens, P. J., & Münck, E. (1994) Biochemistry 33, 14475-14485], the spectroscopic and redox properties of NEM-modified FTR are interpreted in terms of a [4Fe-4S]2+ cluster covalently attached through a cluster sulfide to a cysteine-based thiyl radical formed on one of the active-site thiols. A mechanistic scheme for FTR is proposed with similarities to that established for the well-characterized NAD(P)H-dependent flavin-containing disulfide oxidoreductases, but involving sequential one-electron redox processes with the role of the [4Fe-4S]2+ cluster being to stabilize the thiyl radical formed by the initial one-electron reduction of the active-site disulfide. The results indicate a new biological role for Fe-S clusters involving both the stabilization of a thiyl radical intermediate and cluster site-specific chemistry involving a bridging sulfide. << Less
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Regulation of CO2 assimilation in oxygenic photosynthesis: the ferredoxin/thioredoxin system. Perspective on its discovery, present status, and future development.
Buchanan B.B.
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Amino acid sequence of spinach ferredoxin:thioredoxin reductase catalytic subunit and identification of thiol groups constituting a redox-active disulfide and a [4Fe-4S] cluster.
Chow L.-P., Iwadate H., Yano K., Kamo M., Tsugita A., Gardet-Salvi L., Stritt-Etter A.-L., Schuermann P.
Ferredoxin:thioredoxin reductase is a [4Fe-4S] protein involved in the light regulation of carbon metabolism in oxygenic photosynthesis. This enzyme catalyses the reduction of thioredoxins with light-generated electrons. Ferredoxin:thioredoxin reductase is composed of two dissimilar subunits, a ca ... >> More
Ferredoxin:thioredoxin reductase is a [4Fe-4S] protein involved in the light regulation of carbon metabolism in oxygenic photosynthesis. This enzyme catalyses the reduction of thioredoxins with light-generated electrons. Ferredoxin:thioredoxin reductase is composed of two dissimilar subunits, a catalytic subunit, and a variable subunit. The catalytic subunit of spinach ferredoxin:thioredoxin reductase, which contains the redox-active disulfide bridge, was sequenced by conventional protein sequencing techniques and the functional roles of all eight cysteine residues were examined by chemical modifications. The polypeptide chain with a calculated molecular mass of 12,959 Da consists of 113 amino acids and has a calculated isoelectric point of 5.30. Six of the eight cysteine residues are clustered as Cys-Pro-Cys and Cys-His-Cys groups. Cys19 and Cys27 are free cysteines with no catalytic function, Cys54 and Cys84 constitute the redox-active disulfide bridge of the active site, and the remaining four, Cys52, Cys71, Cys73, and Cys82 bind the Fe-S cluster. << Less