Discussion 275 



swelling process which occurs in heart sarcosomes under carefully 

 defined conditions (Beechey, R. B., and Holton, F. A. (1959). Biochem. 

 J., in press). We took care that the extinction changes which we 

 measured were due to morphological changes and not to changes in the 

 oxidation states of respiratory pigments by following extinction changes 

 at three wavelengths simultaneously. The swelling process which we ob- 

 served may be related to some of the effects previously reported by other 

 workers, but it was distinguishable from many of them by the following 

 features. (1) The swelling was observed only under aerobic conditions 

 and was rapidly and completely reversed when conditions became 

 anaerobic. (2) Reversible swelling occurred in sarcosomes exhibiting 

 respiratory control as defined earlier in this meeting by Prof. Chance 

 (i.e. their respiration was accelerated by ADP and it became slower 

 again when the added ADP was exhausted), but reversible swelling did 

 not occur under a variety of conditions where respiratory control was 

 shown to be absent. 



Our observations included the changes of pigment extinction due to 

 reduction of the respiratory chain as oxygen became exhausted, and we 

 were able to show that anaerobic swelling gave place to anaerobic 

 shrinking within a few seconds of the beginning of the shift of the 

 oxidation state of the chain towards its anaerobic level. We also found 

 that gradual loss of respiratory control during ageing was accompanied 

 by a gradual disappearance of the reversible swelling phenomenon, and 

 that a low concentration of DNP (4 • 6 [xm) had the same effect. 



We cannot yet say for sure that the aerobic swelling is due to the 

 entry of inorganic phosphate and ADP into the sarcosome, or that the 

 anaerobic shrinkage is due to their extrusion, but it seems possible that 

 this is so, and that the observed link between reversible swelling and 

 respiratory control represents part of the mechanism which controls the 

 distribution of phosphate and adenine nucleotides within the cell. 



Holzer: Prof. Lynen, are hexokinase and phosphofructokinase local- 

 ized in the particles which can be obtained from yeast cells with your 

 method? 



Lynen: Dr. Bryant (unpublished experiments) investigated the dis- 

 tribution of both kinases, using yeast cells disintegrated in the Nossal 

 shaker. When he determined the ratio of hexokinase to phospho- 

 fructokinase in the particulate fraction and in the supernatant, he 

 found no difference. I may add that the activity of both enzymes in the 

 isolated particles was extremely low. 



Hess: The Pasteur effect might be differentiated from ours and 

 Crabtree's effect as follows. In the Pasteur effect you change the 

 electron acceptor; you switch from oxygen to nitrogen, so that all the 

 electrons which might go to oxygen go, in fact, to other metabolites. If 

 you add glucose to aerobic cells, e.g. ascites cells, you switch from one 

 type of endogenous substrate to another one, namely to glucose and its 

 degradation products, by reason of the fact that you add glucose and, 

 therefore, also glycolytic intermediates which had not been in the cells 

 before (at least not in appreciable amounts). I don't think that we can 

 expect the same kind of transition in metabolism in Pasteur's and our 



