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X-ray Absorption Spectroscopy Reveals an Organometallic Ni–C Bond in the CO-Treated Form of Acetyl-CoA Synthase
- Source :
- Biochemistry. 56:1248-1260
- Publication Year :
- 2017
- Publisher :
- American Chemical Society (ACS), 2017.
-
Abstract
- Acetyl-CoA synthase (ACS) is a key enzyme in the Wood–Ljungdahl pathway of anaerobic CO2 fixation, which has long been proposed to operate by a novel mechanism involving a series of protein-bound organometallic (Ni–CO, methyl–Ni, and acetyl–Ni) intermediates. Here we report the first direct structural evidence of the proposed metal–carbon bond. We describe the preparation of the highly active metal-replete enzyme and near-quantitative generation of the kinetically competent carbonylated intermediate. This advance has allowed a combination of Ni and Fe K-edge X-ray absorption spectroscopy and extended X-ray absorption fine structure experiments along with density functional theory calculations. The data reveal that CO binds to the proximal Ni of the six-metal metallocenter at the active site and undergoes dramatic structural and electronic perturbation in forming this organometallic Ni–CO intermediate. This direct identification of a Ni–carbon bond in the catalytically competent CO-bound form of the A cluster of ACS provides definitive experimental structural evidence supporting the proposed organometallic mechanism of anaerobic acetyl-CoA synthesis.
- Subjects :
- Models, Molecular
0301 basic medicine
Absorption spectroscopy
Stereochemistry
010402 general chemistry
01 natural sciences
Biochemistry
Article
03 medical and health sciences
chemistry.chemical_compound
Nickel
Catalytic Domain
Coenzyme A Ligases
Organometallic Compounds
Group 2 organometallic chemistry
Carbon Monoxide
X-ray absorption spectroscopy
biology
Chemistry
Acetyl-CoA
Active site
0104 chemical sciences
X-Ray Absorption Spectroscopy
030104 developmental biology
biology.protein
Quantum Theory
Density functional theory
Absorption (chemistry)
Oxidation-Reduction
Carbon monoxide
Subjects
Details
- ISSN :
- 15204995 and 00062960
- Volume :
- 56
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....ac599d3ffa403826694af8ca9427bbf3