title: Synthesis of either Fe- or Mn-superoxide dismutase with an apparently identical protein moiety by an anaerobic bacterium dependent on the metal supplied.
abstract: Superoxide dismutase of Propionibacterium shermanii, an anaerobic that produces an iron superoxide dismutase, was purified from cells grown in iron-free conditions. The enzyme isolated was found to contain manganese and to have spectral and catalytic properties very similar to those of typical Mn-superoxide dismutases. Its electrophoretic mobility, molecular weight, and subunit size were identical with those of the Fe-enzyme. Amino acid compositions were practically indistinguishable in either case. The NH2-terminal sequence was found to be identical. The catalytic activity of an apoprotein sample prepared from the purified holoenzyme was restored by adding either Mn(II) or Fe(II). Only the metal/protein ratio varied from approximately 1 per subunit in the case of the Fe-enzyme to approximately 2 for the Mn-enzyme. It is concluded that this bacterium can accommodate either Fe or Mn on identical, or very slightly dissimilar, proteins forming active sites with the properties found in specific metallodismutases.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000693:Anaerobiosis; D001059:Apoproteins / Q000378:metabolism; D008970:Molecular Weight; D011424:Propionibacterium / Q000201:enzymology*; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000096:biosynthesis* / Q000302:isolation & purification
chemical_list: D000596:Amino Acids; D001059:Apoproteins; D013482:Superoxide Dismutase