A molecular switch in cytochrome C oxidase turns on thermogenesis in heart at low work load.
We describe a new mechanism of respiratory control by ATP on cytochrome c oxidase, which contrasts with the well known respiratory control of the electron transfer chain in mitochondria by ADP/ATP ratios. It is well established that high ADP/ATP ratios stimulate respiration and thus the synthesis of ATP in mitochondria, according to the energy requirements of the cell. Herein we describe the direct stimulation by high ATP/ADP-ratios of bovine heart (but not liver) cytochrome c oxidase activity in reconstituted vesicles. Under these same conditions it has already been shown that ATP decreases the H+/e- stoichiometry of cytochrome oxidase. Thus the observed effect of high ATP on cytochrome c oxidase would be expected to lead to partial uncoupling of energy transduction in mitochondria and to stimulation of thermogenesis.
Belyanovich
L
L
Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
Arnold
S
S
Köhnke
D
D
Kadenbach
B
B
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001833:Body Temperature Regulation; D002417:Cattle; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D008929:Mitochondria, Heart / Q000201:enzymology / Q000502:physiology*; D008930:Mitochondria, Liver / Q000201:enzymology / Q000502:physiology
D006153:Guanosine Diphosphate; D000244:Adenosine Diphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D003576:Electron Transport Complex IV