Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
a [DsrC protein]-S-sulfanyl-L-cysteine + 2 acceptor + 3 H2O = sulfite + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
(1b)
-
-
-
a [DsrC protein]-S-sulfanyl-L-cysteine + 3 acceptor + 3 H2O = a [DsrC]-S-sulfo-L-cysteine + 3 reduced acceptor + H+
(2a)
-
-
-
a [DsrC protein]-S-sulfanyl-L-cysteine + 3 acceptor + 3 H2O = sulfite + a [DsrC protein]-disulfide + 3 reduced acceptor + 2 H+
(2), overall reaction
-
-
-
a [DsrC]-S-sulfo-L-cysteine = sulfite + a [DsrC protein]-disulfide
(2b)
-
-
-
hydrogen sulfide + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O = sulfite + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
hydrogen sulfide + a [DsrC protein]-disulfide = a [DsrC protein]-S-sulfanyl-L-cysteine
(1a)
-
-
-
hydrogen sulfide + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O = sulfite + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
(1), overall reaction
-
-
-
hydrogen sulfide + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O = sulfite + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
sulfite is bound at an oxidation state of S1IV and immediately dehydrated. All oxygen atoms are fixed in a tight hydrogen-bonding network, upon transfer of two electrons to yield an S1II state, a second oxygen atom is released as water, but held within the active-site cavity. A further two-electron reduction leads to the S0 state, weakening the remaining S-O bond. With the final transfer of two electrons, the state of sulfide (S2II) is reached and a third water is released, catalytic mechanism overview. The heterobimetallic active-site heme 2 has a Cu(I) ion juxtaposed to a heme c at a Fe-Cu distance of 4.4 A. While the combination of metals is reminiscent of respiratory heme-copper oxidases, the oxidation-labile Cu(I) centre of MccA does not seem to undergo a redox transition during catalysis. Intact MccA tightly binds SO2 at heme 2, a dehydration product of the substrate sulfite that is partially turned over due to photoreduction by X-ray irradiation, yielding the reaction intermediate SO. Structure of sulfite reduction at heme2 of MccA, sulfite binds to the resting state of the enzyme, but the active-site architecture shifts the reversible dehydration equilibrium to SO2 + H2O. Reduction by two electrons occurs through photoreduction in the X-ray beam and leads to release of a second H2O after protonation, with SO remaining bound to the active site. A tight network of hydrogen bonds surrounds the bimetal centre and the bound substrate, holding the reaction products in place. The sulfite substrate only oxidizes half the heme groups of reduced MccA, emphasizing that the total electron charge of the multiheme enzyme is of high relevance for catalysis
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
hydroxylamine + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
? + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O
nitrite + a [DsrC protein]-dithiol + 2 reduced acceptor
? + a [DsrC protein]-disulfide + 2 acceptor + 2 H2O
SeO32- + a [DsrC protein]-dithiol + 2 reduced methyl viologen + 2 H+
HSe- + a [DsrC protein]-disulfide + 2 oxidized methyl viologen + 3 H2O
-
-
40% of the activity with sulfite
-
?
sulfite + 6 ferrocytochrome c + 6 H+
sulfide + 6 ferricytochrome c + 3 H2O
overall transfer of 6 electrons during the reaction
-
-
?
sulfite + a [DsrC protein]-dithiol + 2 reduced ferredoxin + 2 H+
hydrogen sulfide + a [DsrC protein]-disulfide + 2 oxidized ferredoxin + 3 H2O
sulfite + a [DsrC protein]-dithiol + reduced methyl viologen
trithionate + a [DsrC protein]-disulfide + oxidized methyl viologen
additional information
?
-
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydroxylamine + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
? + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O
-
-
50% of the activity with sulfite
-
?
hydroxylamine + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
? + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O
-
-
-
-
?
hydroxylamine + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+
? + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O
-
-
-
-
?
nitrite + a [DsrC protein]-dithiol + 2 reduced acceptor
? + a [DsrC protein]-disulfide + 2 acceptor + 2 H2O
-
-
25% of the activity with sulfite
-
?
nitrite + a [DsrC protein]-dithiol + 2 reduced acceptor
? + a [DsrC protein]-disulfide + 2 acceptor + 2 H2O
-
-
-
-
?
nitrite + a [DsrC protein]-dithiol + 2 reduced acceptor
? + a [DsrC protein]-disulfide + 2 acceptor + 2 H2O
-
-
-
-
?
sulfite + a [DsrC protein]-dithiol + 2 reduced ferredoxin + 2 H+
hydrogen sulfide + a [DsrC protein]-disulfide + 2 oxidized ferredoxin + 3 H2O
-
-
overall reaction
-
?
sulfite + a [DsrC protein]-dithiol + 2 reduced ferredoxin + 2 H+
hydrogen sulfide + a [DsrC protein]-disulfide + 2 oxidized ferredoxin + 3 H2O
-
-
overall reaction
-
?
sulfite + a [DsrC protein]-dithiol + 2 reduced ferredoxin + 2 H+
hydrogen sulfide + a [DsrC protein]-disulfide + 2 oxidized ferredoxin + 3 H2O
-
-
overall reaction
-
?
sulfite + a [DsrC protein]-dithiol + reduced methyl viologen
trithionate + a [DsrC protein]-disulfide + oxidized methyl viologen
-
-
trithionate is the major product, plus formation of thiosulfate and sulfid
-
?
sulfite + a [DsrC protein]-dithiol + reduced methyl viologen
trithionate + a [DsrC protein]-disulfide + oxidized methyl viologen
-
-
trithionate is the major product, plus formation of thiosulfate and sulfid
-
?
sulfite + a [DsrC protein]-dithiol + reduced methyl viologen
trithionate + a [DsrC protein]-disulfide + oxidized methyl viologen
-
-
trithionate is the major product with reduced methyl viologen as electron donor
-
?
additional information
?
-
-
no substrates: S3O62-, S2O32-. Methyl viologen is as effective as ferredoxin in coupling the sulfite reductase with hydrogenase while benzyl viologen is only 16% as effective as ferredoxin. No activity is observed with NAD, NADP, FAD or FMN. Varying the substrate concentration [SO 2-] from 1 to 2.5 micromol affects the stoichiometry of the enzyme reaction by alteration of the ratio of H2 uptake to S2- formed from 2.5:1 to 3.1:1
-
-
?
additional information
?
-
the enzyme catalyzes the reduction of sulfite to sulfide
-
-
-
additional information
?
-
the enzyme catalyzes the reduction of sulfite to sulfide
-
-
-
additional information
?
-
the enzyme catalyzes the reduction of sulfite to sulfide
-
-
-
additional information
?
-
-
two-state hypothesis for enzyme activity: an active form (DVa) binds and catalyzes substrate reduction, and an inactive form (DVi) exists for the resting enzyme. Only the active form of the enzyme need be considered during steady-state turnover. Determination of the rate constants defining these structural perturbations, from oxidized to reduced and reduced to oxidized states
-
-
?
additional information
?
-
-
two-state hypothesis for enzyme activity: an active form (DVa) binds and catalyzes substrate reduction, and an inactive form (DVi) exists for the resting enzyme. Only the active form of the enzyme need be considered during steady-state turnover. Determination of the rate constants defining these structural perturbations, from oxidized to reduced and reduced to oxidized states
-
-
?
additional information
?
-
multiheme cytochrome c enzymes catalyse complex-multi-electron redox reactions and bind their substrates through the free electron pairs of a heteroatom to a free coordination position at an active-site hem group. Electrons are then provided or accepted by the tightly coupled chain of heme groups
-
-
?
additional information
?
-
MccA reduces sulfite, but not arsenate, selenate, selenite, hydroxylamine, hydrazine, fumarate, nitrate, thiosulfate, tetrathionate, polysulfide, or Fe(III). Nitrite is reduced only very slowly to ammonium
-
-
?
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
sulfite + 6 ferrocytochrome c + 6 H+
sulfide + 6 ferricytochrome c + 3 H2O
overall transfer of 6 electrons during the reaction
-
-
?
additional information
?
-
multiheme cytochrome c enzymes catalyse complex-multi-electron redox reactions and bind their substrates through the free electron pairs of a heteroatom to a free coordination position at an active-site hem group. Electrons are then provided or accepted by the tightly coupled chain of heme groups
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
hydrogen sulfide + a [DsrC protein]-disulfide + acceptor + H2O
sulfite + a [DsrC protein]-dithiol + reduced acceptor + H+
-
-
-
-
?
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
cytochrome c
octaheme cytochrome
heme
octaheme cytochrome, a homotrimer with an unprecedented fold and heme arrangement, as well as a heme bound to a CX15CH motif. The heterobimetallic active-site heme 2 has a Cu(I) ion juxtaposed to a heme c at a Fe-Cu distance of 4.4 A, active-site heme 2 is bound to a canonical CXXCH motif with H306 as a proximal axial ligand. In the CX15CH motif of heme 8, the extended region between the two cysteine residues forms a loop with a short helical turn, in direct vicinity to another loop harbouring the only non-proline cis peptide in the enzyme, between residues G508 and F509. Its formation might require the essential peptidyl isomerase MccB2, and it is presumed to be a prerequisite for correct folding of the loop in the maturation process of heme 8, which is likely to be attached by the dedicated cytochrome c synthase CcsA1. The structure of the CX15CH heme c binding motif disrupts the general parallel/perpendicular heme stacking sequence, and rotates the heme out of plane, possibly to optimize the interaction with the putative electron donor, the iron-sulfur protein MccC
additional information
-
no activity is observed with NAD, NADP, FAD or FMN
-
siroheme
-
at least two of three subunits contain two pairs of [Fe4-S4]-centers and siroheme units
siroheme
O93650; O93651
binding of two sirohemes and four [4Fe-4S]-clusters per alpha2beta2 structure
siroheme
Q9ZH18; Q9ZH17
binding of two sirohemes and four [4Fe-4S]-clusters per alpha2beta2 structure
siroheme
-
close to 80% of the siroheme moiety in the enzyme is demetallated
siroheme
-
cofactor is extensivel demetallated
siroheme
-
four sirohemes per enzyme molecule
siroheme
protein complex contains two siroheme-[4Fe4S] cofactors bound by subunit DsrB, two sirohydrochlorins and two [4Fe-4S]-centers bound by subunit DsrA, and another four [4Fe-4S]-centers in the ferredoxin domains
siroheme
protein contains high-spin siroheme
[4Fe-4S]-center
-
at least two of three subunits contain two pairs of [Fe4-S4]-centers and siroheme units
[4Fe-4S]-center
O93650; O93651
binding of two sirohemes and four [4Fe-4S]-clusters per alpha2beta2 structure
[4Fe-4S]-center
Q9ZH18; Q9ZH17
binding of two sirohemes and four [4Fe-4S]-clusters per alpha2beta2 structure
[4Fe-4S]-center
-
four centers per enzyme molecule
[4Fe-4S]-center
-
presence of a spin 9/2 iron-sulfur cluster
[4Fe-4S]-center
protein complex contains two siroheme-[4Fe4S] cofactors bound by subunit DsrB, two sirohydrochlorins and two [4Fe-4S]-centers bound by subunit DsrA, and another four [4Fe-4S]-centers in the ferredoxin domains
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
1.8.99.5 dissimilatory sulfite reductase
more
top
