The nitrogenase FeMo-cofactor and P-cluster pair: 2. 2 [Angstrom] resolution structures

Journal Article · Fri May 07 04:00:00 EDT 1993 · Science (Washington, D.C.); (United States)

DOI:https://doi.org/10.1126/science.8484118· OSTI ID:6305677

Chan, M K; Kim, Jongsun; Rees, D C ^[1]

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1. California Inst. of Technology, Pasadena (United States)

Structures recently proposed for the FeMo-cofactor and P-cluster pair of the nitrogenase molybdenum-iron (MoFe)-protein from Azotobacter vinelandii have been crystallographically verified at 2.2 angstrom resolution. Significantly, no hexacoordinate sulfur atoms are observed in either type of metal center. Consequently, the six bridged iron atoms in the FeMo-cofactor are trigonally coordinated by nonprotein ligands, although there may be some iron-iron bonding interactions that could provide a fourth coordination interaction for these sites. Two of the cluster sulfurs in the P-cluster pair are very close together ([approximately]2.1 angstroms), indicating that they form a disulfide bond. These findings indicate that a cavity exists in the interior of the FeMo-cofactor that could be involved in substrate binding and suggest that redox reactions at the P-cluster pair may be linked to transitions of two cluster-bound sulfurs between disulfide and sulfide oxidation states. 12 refs., 3 figs.

• OSTI ID: 6305677
• Journal Information: Science (Washington, D.C.); (United States), Journal Name: Science (Washington, D.C.); (United States) Vol. 260:5109; ISSN SCIEAS; ISSN 0036-8075
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AZOTOBACTER
BACTERIA
COORDINATION NUMBER
CRYSTAL STRUCTURE
ELEMENTS
ENZYMES
IRON
METALS
MICROORGANISMS
MOLECULAR CLUSTERS
MOLYBDENUM
NITRO-GROUP DEHYDROGENASES
NITROGENASE
NONMETALS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PROTEINS
SULFUR
TRANSITION ELEMENTS