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Assignment of protonated R-homocitrate in extracted FeMo-cofactor of nitrogenase via vibrational circular dichroism spectroscopy.
- Source :
-
Communications Chemistry . 10/28/2020, Vol. 3 Issue 1, pN.PAG-N.PAG. 1p. - Publication Year :
- 2020
-
Abstract
- Protonation of FeMo-cofactor (FeMo-co) is important for the process of substrate hydrogenation. Its structure has been clarified as Δ-Mo*Fe7S9C(R-homocit*)(cys)(Hhis) after the efforts of nearly 30 years, but it remains controversial whether FeMo-co is protonated or deprotonated with chelated ≡C − O(H) homocitrate. We have used protonated molybdenum(V) lactate 1 and its enantiomer as model compounds for R-homocitrate in FeMo-co of nitrogenase. Vibrational circular dichroism (VCD) spectrum of 1 at 1051 cm−1 is attributed to ≡C − OH vibration, and molybdenum(VI) R-lactate at 1086 cm−1 is assigned as ≡C − Oα-alkoxy vibration. These vibrations set up labels for the protonation state of coordinated α-hydroxycarboxylates. The characteristic VCD band of NMF-extracted FeMo-co is assigned to ν(C − OH), which is based on the comparison of molybdenum(VI) R-homocitrate. Density functional theory calculations are consistent with these assignments. To the best of our knowledge, this is the first time that protonated R-homocitrate in FeMo-co is confirmed by VCD spectra. The nitrogenase FeMo-cofactor is chelated by homocitrate, but the protonation state of this key ligand is debated. Here vibrational circular dichroism studies of the extracted cofactor suggest that it is protonated. [ABSTRACT FROM AUTHOR]
- Subjects :
- *CIRCULAR dichroism
*COFACTORS (Biochemistry)
*ENANTIOMERS
*NITROGENASES
*MOLYBDENUM
Subjects
Details
- Language :
- English
- ISSN :
- 23993669
- Volume :
- 3
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Communications Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 146680860
- Full Text :
- https://doi.org/10.1038/s42004-020-00392-z