FERMENTATION AND GLYCOLYSIS 875 



glycogen, ATP, and NAD added) is completely blocked. Similar results 

 were obtained with sea urchin eggs by Cleland and Rothschild (1952 a), 

 1 mM PM inhibiting lactate formation 17% in whole eggs and 97% in 

 extracts. These results were interpreted to indicate poor penetration by the 

 mercurial, but the other two explanations given above are probably as 

 likely, and undoubtedly all contribute to some extent. It may be noted that 

 Cleland found endogenous respiration to be inhibited more potently in 

 whole eggs than in homogenates, which is more difficult to explain. There 

 are instances of cellular glycolysis quite sensitive to the mercurials; in asci- 

 tes carcinoma cells there is 50% inhibition by 0.0032 mM Hg++ (Schom 

 et at., 1961). The glycolysis in spleen slices is also fairly sensitive, although 

 it requires 4-5 hr to reach maximal inhibition (Fig. 1-12-24) (Jowett and 

 Brooks, 1928). The interesting questions of the penetration of mercurials 

 and the effects exerted on cell membranes will be considered later (page 892). 



Yeast Fermentation 



Since the early work of Schulz (1888), who reported an initial stimulation 

 of fermentation by low concentrations of Hg++ (0.005-0.008 mM) and inhi- 

 bition by higher concentrations (> 0.02 mM), there have been many stud- 

 ies of yeast fermentation with variable results. The stimulation observed 

 by Schulz has seldom been confirmed. Joachimoglu (1922) could never dem- 

 onstrate acceleration of CO2 formation by Hg++, concentrations of 0.0031- 

 0.037 mM exerting no effect and 0.074 mM inhibiting around 70%. Meier 

 (1926) found even more potent inhibition of aerobic fermentation, 0.009 mM 

 Hg++ depressing 72%, while Kostytschew and Berg (1930) never observed 

 stimulation, inhibition beginning at 0.0185 mM Hg++ and reaching 42% 

 at 0.2 mM. More recently, some have found potent inhibition by Hg++ 

 (e.g., Hurwitz and Chaffee, 1954), but others have not (e.g., Weitzel and 

 Buddecke, 1959); in the latter work, 1 mM Hg++ inhibited only 70% in 

 fermenting yeast. Organic mercurials have not been often used, but Spiegel- 

 man et al. (1948) reported 69% inhibition by 0.01 mM PM and 32% inhi- 

 bition by 0.05 mM p-MB, indicating these mercurials to be fairly effective. 

 Certainly much of the variation in the results is due to the different densi- 

 ties of yeast suspension used, the media employed, and the state of the 

 yeast (by which is meant its fermentative activity and past history). One 

 would expect mercurials to attack surface hexokinase and the initial phos- 

 phorylation of glucose, as occurs in muscle, so one can explain the exam- 

 ples of weak inhibition only on the basis of relatively dense yeast suspen- 

 sions. 



Muscle Glycolysis 



The results obtained on muscle glycolysis with the mercurials have been 

 quite inconsistent and even more difficult to explain than those with yeast. 



