Modulation of cytochrome oxidase kinetics by indirect antibody action.
Polyclonal antibodies raised against isolated subunit V from beef heart cytochrome oxidase or against the intact enzyme increase its apparent affinity for the substrate cytochrome c at the high-affinity site while diminishing the turnover at that site. At the low-affinity site the major action of both types of antibody is to reduce the apparent affinity for cytochrome c. At high ionic strengths the kinetic effect of anti-subunit V is very small although it still binds to the enzyme. The results are interpreted in terms of a model for the enzyme in which antibodies can modulate cytochrome oxidase kinetics by affecting the binding of cytochrome c, even if the antibody-binding site is on a subunit not directly involved in substrate binding.
Nicholls
P
P
Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada.
Cooper
C E
CE
D000818:Animals; D000906:Antibodies / Q000276:immunology; D002417:Cattle; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors / Q000276:immunology*; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology*; D005719:gamma-Globulins / Q000276:immunology
D000906:Antibodies; D005719:gamma-Globulins; D003576:Electron Transport Complex IV