Why does sulfite reductase employ siroheme?
(2019) In Chemical Communications 55(93). p.14047-14049- Abstract
Sulfite reductase (SiR) contains in the active site a unique assembly of siroheme and a [4Fe4S] cluster, linked by a cysteine residue. Siroheme is a doubly reduced variant of heme that is not used for a catalytic function in any other enzyme. We have used non-equilibrium Green's function methods coupled with density functional theory computations to explain why SiR employs siroheme rather than heme. The results show that direct, through vacuum, charge-transfer routes are inhibited when heme is replaced by siroheme. This ensures more efficient channelling of the electrons to the catalytic iron during the six-electron reduction of sulfite to sulfide, limiting potential side-reactions that could occur if the incoming electrons were... (More)
Sulfite reductase (SiR) contains in the active site a unique assembly of siroheme and a [4Fe4S] cluster, linked by a cysteine residue. Siroheme is a doubly reduced variant of heme that is not used for a catalytic function in any other enzyme. We have used non-equilibrium Green's function methods coupled with density functional theory computations to explain why SiR employs siroheme rather than heme. The results show that direct, through vacuum, charge-transfer routes are inhibited when heme is replaced by siroheme. This ensures more efficient channelling of the electrons to the catalytic iron during the six-electron reduction of sulfite to sulfide, limiting potential side-reactions that could occur if the incoming electrons were delocalized onto the macrocyclic ring.
(Less)
- author
- Brânzanic, Adrian M.V. ; Ryde, Ulf LU and Silaghi-Dumitrescu, Radu
- organization
- publishing date
- 2019
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Chemical Communications
- volume
- 55
- issue
- 93
- pages
- 3 pages
- publisher
- Royal Society of Chemistry
- external identifiers
-
- pmid:31690895
- scopus:85075221789
- ISSN
- 1359-7345
- DOI
- 10.1039/c9cc05271b
- language
- English
- LU publication?
- yes
- id
- 988a069d-1d68-4feb-a772-898b80f6bf92
- date added to LUP
- 2019-12-10 08:50:14
- date last changed
- 2024-08-07 11:09:08
@article{988a069d-1d68-4feb-a772-898b80f6bf92, abstract = {{<p>Sulfite reductase (SiR) contains in the active site a unique assembly of siroheme and a [4Fe4S] cluster, linked by a cysteine residue. Siroheme is a doubly reduced variant of heme that is not used for a catalytic function in any other enzyme. We have used non-equilibrium Green's function methods coupled with density functional theory computations to explain why SiR employs siroheme rather than heme. The results show that direct, through vacuum, charge-transfer routes are inhibited when heme is replaced by siroheme. This ensures more efficient channelling of the electrons to the catalytic iron during the six-electron reduction of sulfite to sulfide, limiting potential side-reactions that could occur if the incoming electrons were delocalized onto the macrocyclic ring.</p>}}, author = {{Brânzanic, Adrian M.V. and Ryde, Ulf and Silaghi-Dumitrescu, Radu}}, issn = {{1359-7345}}, language = {{eng}}, number = {{93}}, pages = {{14047--14049}}, publisher = {{Royal Society of Chemistry}}, series = {{Chemical Communications}}, title = {{Why does sulfite reductase employ siroheme?}}, url = {{https://lup.lub.lu.se/search/files/84187867/259_siroheme.pdf}}, doi = {{10.1039/c9cc05271b}}, volume = {{55}}, year = {{2019}}, }