722 6. O-IODOSOBENZOATE 



Table 6-2 

 Effects of o-Iodosobenzoate on Glycolysis in Muscle Homogenates" 



Conditions ''^™^ Zl pH A ATP A CrP J FrPP A TrioseP 



(mm) 



" The values for the phosphate fractions are changes in the per cents of the total 

 acid-soluble phosphorus. (From Bailey and Marsh, 1952.) 



may stimulate, a phenomenon seen with other SH reagents (HgClg, js-chloro- 

 mercuribenzoate, arsenite, and iodoacetamide) (Barron et al., 1948). The 

 respiration of Ehrlich ascites tumor cells is inhibited 50% by 0.35 mM 

 o-iodosobenzoate, 0.1 mM inhibiting 11% and 1 mM 93% (Shacter, 1957). 

 Thus the susceptibility of respiration is confirmed but there are no data 

 for locating the principal sites of action. 



The binding of K+ in liver mitochondria is believed by Gamble (1957) to 

 be related to the sites for oxidative phosphorylation, although it is not 

 directly dependent on ATP. The evidence comes from the ability of 2,4- 

 dinitrophenol to lower mitochondrial K+ markedly. o-Iodosobenzoate at 

 0.03 mM produces effects similar to 2,4-dinitrophenol, which does not nec- 

 essarily imply an uncoupling action of the o-iodosobenzoate, but indicates 

 some effect on the electron transport chain. Scott and Gamble (1961) have 

 found mercurials to stimulate the K+ exchange rate of mitochondria and 

 simultaneously to reduce the bound K+. These effects are also produced by 

 o-iodosobenzoate: the exchange rate is doubled by 0.08 mM, the mitochon- 

 drial K+ is half reduced by 0.15 mM, and oxidative phosphorylation is 50% 

 inhibited by 0.08 mM. These potent actions of o-iodosobenzoate point to 

 important effects on mitochondrial oxidative systems that apparently play 

 a role in the depression of respiration. 



