CONTROL POINTS IN PHOSPHORYLATING 



RESPIRATION AND THE ACTION OF A 



MITOCHONDRIAL RESPIRATION-RELEASING 



FACTOR* 



Albert L. Lehninger, Charles L. Wadkins and 

 LeMar F. Remmert 



Department of Physiological Chemistry, The Johns Hopkins 

 School of Medicine, Baltimore, Md. 



This paper outlines recent work in this laboratory on the 

 sequence and character of the terminal reactions by which 

 adenosine triphosphate (ATP) is formed during respiratory 

 chain phosphorylation, the site of action of some classical 

 uncoupling agents, and the effects of a naturally occurring 

 mitochondrial agent capable of controlling some aspects of the 

 coupling of phosphorylation to respiration. 



Exchange reactions of ATP and the sequence of coupling 

 reactions 



Earlier work has shown that submitochondrial fragments 

 prepared with digitonin contain more or less intact respiratory 

 chains and couple phosphorylation of adenosine diphosphate 

 (ADP) to electron transport at three sites with reasonably high 

 efficiency (Cooper and Lehninger, 1956a and h; Devlin and 

 Lehninger, 1956, 1958; Devlin, 1959; Lehninger et al, 1958). 

 Such preparations catalyse two exchange reactions of ATP 

 in the absence of net electron transport which are reflections 

 of the energy-coupling mechanism. 



In the ATP-^2p. (p. ^ inorganic phosphate) exchange 

 reaction, orthophosphate labelled with ^^p js incorporated 

 into the terminal phosphate of ATP (Cooper and Lehninger, 

 19575), and this reaction may proceed to isotopic equilibrium. 



* This work was supported by grants from the U.S. Public Health Service 

 and The Nutrition Foundation, Inc. 



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