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Putative reaction m...
Putative reaction mechanism of nitrogenase after dissociation of a sulfide ligand
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- Cao, Lili (författare)
- Lund University,Lunds universitet,Beräkningskemi,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Computational Chemistry,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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- Ryde, Ulf (författare)
- Lund University,Lunds universitet,Beräkningskemi,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Computational Chemistry,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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(creator_code:org_t)
- Elsevier BV, 2020
- 2020
- Engelska 13 s.
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Ingår i: Journal of Catalysis. - : Elsevier BV. - 1090-2694 .- 0021-9517. ; 391, s. 247-259
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Abstract
Ämnesord
Stäng
- We have investigated the implications of the recent crystallographic findings that the m2-bridging S2B sulfide ligand may reversibly dissociate from the active-site FeMo cluster of nitrogenase. We show with combined quantum mechanical and molecular mechanical (QM/MM) calculations that once S2B has dis- sociated, N2 may bind in that position and can be protonated to two NH3 groups by thermodynamically favourable steps. The substrate forms hydrogen bonds with two protein ligands, Gln-191 and His-195. For all steps, we have studied three possible protonation states of His-195 (protonated on either ND1, NE2 or both). We find that the thermodynamically favoured path involves an end-on NNH2 structure, a mixed side-on/end-on H2NNH structure, a side-on H2NNH2 structure, a bridging NH2 structure and a bridging NH3 structure. In all cases, His-195 seems to be protonated on the NE2 atom. Dissociation of the NH3 pro- duct is often unfavourable and requires either further reduction or protonation of the cluster or rebinding of S2B. In conclusion, our calculations show that dissociation of S2B gives rise to a natural binding and reaction site for nitrogenase, between the Fe2 and Fe6 atoms, which can support an alternating reaction mechanism with favourable energetics.
Ämnesord
- NATURVETENSKAP -- Kemi -- Teoretisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)
Nyckelord
- Nitrogenase
- QM/MM
- S2B dissociation
- Nitrogen fixation
- Alternating or distal reaction mechanism
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)
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