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

Journal Article · Fri May 07 00:00:00 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), Vol. 260:5109; ISSN 0036-8075
• Country of Publication: United States
• Language: English

Related Subjects

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