Biomaterial Database

The vanadium-iron protein of vanadium nitrogenase from Azotobacter chroococcum contains an iron-vanadium cofactor. 1988

B E Smith, and R R Eady, and D J Lowe, and C Gormal

A.F.R.C. I.P.S.R. Nitrogen Fixation Laboratory, University of Sussex, Brighton, U.K.

N-Methylformamide extracts of acid-treated precipitated VFe protein of the V-nitrogenase of Azotobacter chroococcum are yellow-brown in colour and contain vanadium, iron and acid-labile sulphur in the approximate proportions 1:6:5. E.p.r. spectra of the extracts exhibit a weak signal with g values near 4.5, 3.6 and 2.0 characteristic of an S = 3/2 metal-containing centre. The N-methylformamide extracts activated the MoFe protein polypeptides from mutants of nitrogen-fixing bacteria unable to synthesize FeMoco, the active centre of Mo-nitrogenase. The active hybrid protein exhibited the characteristic substrate-reducing phenotype associated with the VFe protein except that it could not reduce N2 to NH3. The above data are interpreted as demonstrating the existence of an iron- and vanadium-containing cofactor, FeVaco, within the VFe protein. It is suggested that nitrogen fixation requires specific interactions between FeVaco or FeMoco and their respective polypeptides. The biosynthesis of these cofactors is discussed.

UI	MeSH Term	Description	Entries
D007501	Iron	A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.	Iron-56,Iron 56
D008667	Metalloproteins	Proteins that have one or more tightly bound metal ions forming part of their structure. (Dorland, 28th ed)	Metalloprotein
D008983	Molybdoferredoxin	A non-heme iron-sulfur protein isolated from Clostridium pasteurianum and other bacteria. It is a component of NITROGENASE, which is active in nitrogen fixation, and consists of two subunits with molecular weights of 59.5 kDa and 50.7 kDa, respectively.	Molybdenum-Iron Protein,FeMo Cofactor,Iron-Molybdenum Cofactor,MoFe Protein,Iron Molybdenum Cofactor,Molybdenum Iron Protein
D009591	Nitrogenase	An enzyme system that catalyzes the fixing of nitrogen in soil bacteria and blue-green algae (CYANOBACTERIA). EC 1.18.6.1.	Dinitrogenase,Vanadium Nitrogenase,Nitrogenase, Vanadium
D004578	Electron Spin Resonance Spectroscopy	A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.	ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D001395	Azotobacter	A genus of gram-negative, aerobic bacteria found in soil and water. Its organisms occur singly, in pairs or irregular clumps, and sometimes in chains of varying lengths.
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D014639	Vanadium	A metallic element with the atomic symbol V, atomic number 23, and atomic weight 50.94. It is used in the manufacture of vanadium steel. Prolonged exposure can lead to chronic intoxication caused by absorption usually via the lungs.	Vanadium-51,Vanadium 51