title: Nitrogenase of Klebsiella pneumoniae. Interaction of the component proteins studied by ultracentrifugation.
abstract: Sedimentation-velocity analyses of mixtures of the component proteins of nitrogenase of Klebsiella pneumoniae at a 1:1 molar ratio, showed a single peak of sedimentation coefficient (12.4S) considerably greater than that obtained for the larger (Fe+Mo-containing) protein centrifuged alone (10.4S). When the ratio exceeded 1:1 (the smaller Fe-containing protein in excess) an additional peak corresponding in sedimentation coefficient (about 4.5S) to free Fe-containing protein appeared. When proteins, which had been inactivated by exposure to air were used, no interaction occurred. Na(2)S(2)O(4) at 2mm both reversed and prevented interaction between the two proteins; sedimentation coefficients corresponded to those of the proteins when centrifuged alone. These results demonstrate the formation of a complex between the nitrogenase proteins, and, together with data of activity titration curves, are consistent with the formulation of the nitrogenase complex of K. pneumoniae as (Fe-containing protein)-(Fe+Mo-containing protein).
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D007501:Iron; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D008982:Molybdenum; D009591:Nitrogenase / Q000378:metabolism*; D011489:Protein Denaturation; D014461:Ultracentrifugation
chemical_list: D001426:Bacterial Proteins; D008982:Molybdenum; D007501:Iron; D009591:Nitrogenase