Superoxide dismutase sources

The ability of PMNs to elaborate O and its reactive progeny and the capacity of these progeny to react with many components of cells attracted the interest of investigators of the molecular basis of the inflammatory response. One way in which PMNs may participate is by acting as the source of the molecules such as OH which may destroy tissue. The inhibition of the inflammatory effects of Carrageenan by superoxide dismutase might represent such an effect. 

Physiological sources Autoxidation of mitochondrial electron carriers Superoxide dismutases (Cu/Zn-, Mn-) H H ... 

While the stoichiometries of the Mn SOD enzymes appear to vary, the properties of the Mn-binding site do not. This is borne out in the electronic spectra of these proteins, which display a great degree of similarity despite the diversity of sources from which they have been isolated (Table II). This type of spectrum is distinctive for manganese in the trivalent oxidation state (3). The native enzymes are EPR silent, as might be anticipated if they contained Mn solely as the trivalent ion (S = 2) (1, 6,12,18-20, 24). However, when the enzymes are denatured, the characteristic six-line pattern of Mn(II) (I = 5/2) appears. Magnetic susceptibility studies with the E. coli SOD were consistent with the presence of a monomeric Mn(III) complex with a zero-field splitting of 1 to 2 cm-1 (4). The enzymes are additionally metal specific (however, see Refs. 36 and 37) metal reconstitution studies with E. coli and B. stearothermophilus revealed a strict requirement for Mn for superoxide dismutase activity (2, 22, 23). 

The reader is referred to the following sources of further information on the specific cocatalytic enzymes superoxide dismutase, and the reduced form, alkahne phosphatases, nuclease Pl, purple acid phosphatase, amidohydrolase, leucine amtnopeptidase, general comments on the mechanisms of the phosphatases and aminopeptidases, and other cocatalytic zinc enzymes. ... 

---