Meier B, Barra D, Bossa F, Calabrese L, Rotilio G
J Biol Chem. 1982 Dec 10;257(23):13977-80.
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.
费氏丙酸杆菌是一种能产生铁超氧化物歧化酶的厌氧菌，其超氧化物歧化酶是从无铁条件下生长的细胞中纯化得到的。所分离出的这种酶被发现含有锰，并且其光谱和催化特性与典型的锰超氧化物歧化酶非常相似。它的电泳迁移率、分子量和亚基大小与铁酶的相同。两种情况下的氨基酸组成实际上难以区分。发现其氨基末端序列相同。通过添加锰（II）或铁（II），由纯化的全酶制备的脱辅基蛋白样品的催化活性得以恢复。只有金属/蛋白质的比例有所不同，铁酶的比例约为每个亚基1个，而锰酶的比例约为2个。结论是，这种细菌能够在相同或非常相似的蛋白质上容纳铁或锰，形成具有特定金属歧化酶特性的活性位点。
