title: Proton pumping and oxidase activity of thermophilic cytochrome oxidase remain after its extensive proteolysis.
abstract: A proton-pumping heme aa3-type cytochrome oxidase purified from the thermophilic bacterium PS3 was treated with trypsin, thermolysin, chymotrypsin, subtilisin, or pronase. The cleavage of the oxidase subunits and the effects of their cleavage on the oxidase activity and proton-pumping in reconstituted vesicles were studied. Trypsin and thermolysin cleaved some of the oxidase subunits without affecting the proton-pumping, but subtilisin and pronase cleaved all the subunits resulting in partial decrease in both activities. Chymotrypsin had an intermediate effect. Subunit II of this enzyme contains heme c which is also cleaved by proteases.
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D001426:Bacterial Proteins / Q000302:isolation & purification; D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D002918:Chymotrypsin; D003576:Electron Transport Complex IV / Q000302:isolation & purification*; D010088:Oxidoreductases / Q000302:isolation & purification* / Q000502:physiology; D010447:Peptide Hydrolases; D011522:Protons; D013820:Thermolysin; D014357:Trypsin
chemical_list: D001426:Bacterial Proteins; D011522:Protons; D010088:Oxidoreductases; D003576:Electron Transport Complex IV; D010447:Peptide Hydrolases; D002918:Chymotrypsin; D014357:Trypsin; D013820:Thermolysin