ENERGY TRANSFER AND CONSERVATION IN 

 THE RESPIRATORY CHAIN 



By B. Chance 



Johnson Research Foundation, University of Pennsylvania, 

 Philadelphia, Pennsylvania 



INTRODUCTION 



Since energy transfer between the respiratory carriers affords an opportunity 

 for conservation of a portion of this energy in intermediate forms and 

 ultimately in adenosine triphosphate (ATP), its mechanism is of fundamental 

 importance. It is the purpose of this paper to examine available experi- 

 mental data and current theories on the nature of the respiratory chain and 

 its relation to energy conservation. The concept of a chain-Uke action of 

 cytochromes was developed early in Keihn's studies (1925, 1927) on the 

 basis of the site of action of urethane and the isolation of cytochrome c, and 

 now appears well estabhshed by both direct kinetic studies of the time 

 sequence of oxidation-reduction reactions (Chance, 1952; Chance and 

 Wilhams, 1955a) and by fragmentation of the respiratory chain (Keilin and 

 Slater, 1953; KeiUn and King, 1958; Green, 1959), although the details of 

 the order of the cytochromes in the sequence, for example cytochromes q 

 and c (Keilin and Hartree, 1955), and the variable function of cytochrome b 

 (Slater, 1950; Tsou, 1951; Chance, 1952, 1958a; Chance and Williams, 

 1955a) have required special study. Indeed, the localization of sites in the 

 respiratory chain at which energy conservation for ATP formation occurs 

 has led to the most widespread investigation of all, and approaches ranging 

 from dispersion in detergents (Lehninger, 1954) or fragmentation (Green, 1959) 

 to pH-activity relationships (Hiilsmann and Slater, 1957) have been employed. 

 However, the spectroscopic response of the carriers to the presence or 

 absence of adenosine diphosphate (ADP) or inorganic phosphate still appears 

 to be the only method for indicating interaction sites that is directly apphcable 

 to the intact chain (Chance and Wilhams, 1955b; Chance, 1959a). 



SPEED OF ELECTRON TRANSFER 

 The Oxidation of Ferrocytochrome c 



The great rapidity of interaction of the 'cryptic' haem of cytochrome c 

 with other haemoproteins was recognized in the work of Altschul, Abrams 



597 



