title: Activation of Pseudomonas cytochrome oxidase by limited proteolysis with subtilisin.
abstract: Oxidized Pseudomonas cytochrome oxidase (ferrocytochrome c2: oxygen oxidoreductase; E.C.1.9.3.2) can be digested with subtilisin under controlled conditions that convert the original parent polypeptide chain (Mr on SDS gels approximately equal to 60,000) to a slightly smaller species (Mr on SDS gels approximately equal to 58,000). Under the conditions used (0.33% subtilisin, w/w, pH 7.4), the product formed from the oxidase was relatively stable to further digestion. Cytochrome oxidase activity was assayed at intervals during proteolysis by following the rate of oxidation of Pseudomonas ferrocytochrome c-551 by the enzyme in the presence of oxygen. The activity increased to a plateau that was more than two times the value for an untreated control. These observations suggest that clipping a small peptide from Pseudomonas cytochrome oxidase either facilitates the rate-limiting electron transfer between the intraprotein heme c and heme d1, enhances the interaction of the enzyme with ferrocytochrome c-551, or both.
mesh_terms: D001426:Bacterial Proteins; D003574:Cytochrome c Group / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006418:Heme / Q000378:metabolism; D007700:Kinetics; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D013381:Subtilisins / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D003574:Cytochrome c Group; D006418:Heme; C017167:cytochrome C(551); D003576:Electron Transport Complex IV; D013381:Subtilisins