Manganese bacterially catalyzed

These processes are catalyzed by bacteria and probably involve both inorganic and organic iron and manganese species (22). They may also be strongly controlled by microbial competition between Fe(III) and sulfate-reducing bacteria (27). Associated with these reduction reactions is the reduction of residual sulfate (produced in the oxic zone by bacterially catalyzed reactions) similar to eq 7 (21). 

Bacterial SODs typically contain either nonheme iron (FeSODs) or manganese (MnSODs) at their active sites, although bacterial copper/zinc and nickel SODs are also known (Imlay and Imlay 1996 Chung et al. 1999). Catalases are usually heme-containing enzymes that catalyze disproportionation of hydrogen peroxide to water and molecular oxygen (Eq. 10.2) (Zamocky and Koller 1999 Loewen et al. 2000). 

This enzyme [EC 3.4.11.9] (also known as Xaa-Pro aminopeptidase, X-Pro aminopeptidase, proline amino-peptidase, and aminoacylproline aminopeptidase) catalyzes the hydrolysis of a peptide bond at the iV-terminus of a peptide provided that the iV-terminal amino acyl residue is linked to a prolyl residue by that peptide bond. The enzyme will also act on dipeptides and tripeptides with that same restriction. Either manganese or cobalt is needed as a cofactor. This enzyme appears to be a membrane-bound system in both mammalian and bacterial cells. The protein belongs to the peptidase family M24B. 

Dioxygenase enzymes are known that contain heme iron, nonheme iron, copper, or manganese.The substrates whose oxygenations are catalyzed by these enzymes are very diverse, as are the metal-binding sites so probably several, possibly unrelated, mechanisms operate in these different systems. For many of these enzymes, there is not yet much detailed mechanistic information. However, some of the intradiol catechol dioxygenases isolated from bacterial sources have been studied in great detail, and both structural and mechanistic information is available. These are the systems that will be described here. 

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