Superoxide cyanide-insensitive

Following a stimulation by the yeast cell wall extract zymosan, phagocytosing human leukocytes show an enhanced oxygen consumption, the cyanide-insensitive respiratory burst , after a lag period of 30-40 s. The production of superoxide anions, measured by the reduction of Fe(ni)-cytochrome c, followed the same... 

Superoxide dismutase (SOD) is a widely distributed enzyme that exists in a variety of forms. The copper-zinc enzyme (Cu,ZnSOD) is primarily located in the cytosol of eukaryotic cells. Mitochondria contain, in the matrix space, a distinctive cyanide-insensitive manganese-containing enzyme (MnSOD) similar to that found in prokaryotes. In addition, a ferrienzyme (FeSOD) has been identified in bacteria that is also insensitive to cyanide. Amino acid sequence homologies indicate two families of superoxide dismutases. One of these is composed of the Cu,ZnSODs and the other of MnSODs and FeSODs. All these superoxide dismutases catalyze the same reaction (2H -H O2 -h OJ H2O2 -t- O2) and with comparable efficiency. 

A cyanide-sensitive SOD activity has been reported in T. cruzi (74). Cyanide-insensitive SODs are also present in trypanosomatids, such as C. fasciculata (75) and Trypanosoma brucei (76). The bimodal distribution of superoxide dismutase in T. brucei is similar to that described for other eukaryotes. Both SOD activities in T. brucei are insensitive to 1 mM cyanide (76). The SOD activities of T. brucei, L. tropica and T. cruzi are also cyanide-insensitive but peroxide- and azide-sensitive (77). SOD of C. fasciculata is located in the cytosol and exists in three forms, which may represent three... 

B. divergens) have been reported to contain an endogenous superoxide dismutase that is cyanide-insensitive and inhibited by H2O2 indicating that iron is the cofactor metal... 

SOD catalyses the dismutation (disproportionation) of superoxide 02 + 02" + 2H - C + H202. There are two main types of SOD l.cyanide-sensi-tive, Cu- and Zn-containing, eukaryotic enzymes, M, 31,000-33,000 (2 subunits, M, 16,000) and 2. cyanide-insensitive, Fe- or Mn-containing, prokaryotic enzymes, M, about 40,000 (2 subimits, M, 20,000). SOD from liver mitochondria ccmtains Mn and has M, 80,000 (4 subunits, M, 20,000). The designations prokaryotic and eukaryotic are not applicable in every case Mn-type SOD has been demonstrated in eukaryotes, while cyanide-sensitive SOD is absent from many algae. In contrast to the view widely held... 

The extract of Ginkgo biloba leaves (EGb 761) inhibited both doxorubicin-induced lipid peroxidation of rat brain homogenates and doxorubicin-induced lethality in mice (Chatterjee and Ga-BARD 1982). From the leaves of this eucaryote Duke and Salin (1985) isolated an iron-containing, cyanide-insensitive superoxide dismutase (EC 1. 15.1.1) exhibiting a sensitivity to hydrogen peroxide. A very faint cuprozinc superoxide dismutase... 

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