. Biological structure and function; proceedings. Biochemistry; Cytology. FUNCTION OF FLAVOENZYMES IN ELECTRON TRANSPORT 159 fluoride gave a similar efl^ect. This ATP-effect may be analogous to the eff"ect of ATP in inducing DPN-reduction by succinate, recently observed by Chance and Hagihara [45] in aged pigeon-heart mitochondria. It was brieflv indicated above (Table IX) that oligomycin A did not inhibit (in fact even slightly stimulated) the succinate-linked reduction of acetoacetate in the present system. As shown in Fig. 12, this compound was also able to restore efficiently acetocae
. Biological structure and function; proceedings. Biochemistry; Cytology. FUNCTION OF FLAVOENZYMES IN ELECTRON TRANSPORT 159 fluoride gave a similar efl^ect. This ATP-effect may be analogous to the eff"ect of ATP in inducing DPN-reduction by succinate, recently observed by Chance and Hagihara [45] in aged pigeon-heart mitochondria. It was brieflv indicated above (Table IX) that oligomycin A did not inhibit (in fact even slightly stimulated) the succinate-linked reduction of acetoacetate in the present system. As shown in Fig. 12, this compound was also able to restore efficiently acetocaetate reduction when this was suppressed because of the presence of a terminal phosphate acceptor (in this case ADP, hexokinase and glucose). Oligomycin A has been shown by 20 16. 12 3 4 5 /iq Oligomycin A Fig. 12. Effect of oligomycin A on succinate-linked reduction of acetoacetate in presence of terminal phosphate acceptor (Azzone, Ernster, and Weinbach, unpublished). Experimental conditions as in .ATP-hexokinase-glucose system in Table VIII. Lardy et al. [46] to inhibit mitochondrial respiration under phosphorvlating conditions but not if the phosphorylation is abolished by dinitrophenol; in extending these studies we found that oligomycin A onlv inhibits tightlv- coupled, but not "loosely-coupled", respiration. Furthermore, according to Lardy et al. [46], oligomycin A also strongly inhibits the mitochondrial P,-ATP exchange and dinitrophenol-induced ATPase reactions. From these observations, oligomycin A appears to act by blocking the transfer of phosphate from the primary high-energy bonds to ADP. This mode of action fits logically with the present findings that oligomycin A removed the phosphate acceptor efi^ect from the succinate-linked reduction of acetoacetate. What is more interesting, however, is that the transfer of energy from the sites of the succinate-linked phosphorylations to the site. Please note that these images are extracted from scanned page image
Size: 1681px × 1486px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiver, booksubjectbiochemistry
