title: Antiferromagnetic exchange interaction in the two-iron-two-sulphur ferredoxin from the blue-green alga Spirulina maxima studied with a highly sensitive magnetic balance.
abstract: 1. A highly sensitive magnetic balance of the Faraday type is described. 2. The magnetic susceptibility of the oxidized and reduced forms of the two-iron-two-sulphur ferredoxin from the blue-green alga Spirulina maxima has been measured over a wide temperature range. 3. The results can be interpreted within a simple model involving antiferromagnetically coupled iron atoms at the active site. The coupling, expressed as --J, is estimated to be 182 +/- 20/cm and 98 +5/-10 /cm for the oxidized and reduced forms, respectively.
mesh_terms: D001665:Binding Sites; D000458:Cyanobacteria / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D005288:Ferredoxins / Q000032:analysis*; D008280:Magnetics; D008433:Mathematics; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013696:Temperature
chemical_list: D005288:Ferredoxins