POTASSIUM IN YKAST CELLS 923 



the potassium compounds, which is presumal)ly intimately connected 

 with the metabohc process going on in the yeast cells, ^^ill l)e strongly 

 enhanced and, correspondingly, the incorporation of ^-K in Ihe organic 

 compounds will be accelerated. On this view, it is not so much an increase 

 in the permeability of the cell membrane during intense fermentation 

 which is responsible for the enhanced potassium exchange but the acce- 

 lerated metabolic rate inside the cell. 



It is of interest to remark that Pulver and Verzar (1941) quite 

 recently found that there is an intimate connection between carbo- 

 hydrate metabolism and potassium uptake denoted in this note as 

 "additional uptake" of potassium in contrast to potassium exchange. 

 They found a large amount of potassium to enter the yeast c(>lls after 

 addition of glucose, the potassium leaving again to a large extent after 

 fermentation starts. 



Summary 



The interchange of potassium between yeast and nutrient solution was in- 

 vestigated by using radiopotassium (*-K) as an indicator. 



In strongly fermenting yeast, a full interchange was found to take place between 

 the potassium of the yeast and the potassium of the nutrient solution in the 

 course of 2 hours. In most experiments in which the fermentation was slight, 

 a much slower potassium exchange was observed. 



The effect of fermentation on the rate of potassium exchange is possibly not 

 so much due to an increase in the permeability of the yeast cell membrane to 

 potassium as to an enhanced rate of resynthesis of potassium containing com- 

 pounds under fermentation. Such a process will lead to an acceleration of potassium 

 interchange. 



Literature 



G. Hevesy, K. Lindekstr0m-Lang and N. Nielsen (1937) Nature, 'Land. 140, 



726. 



J. M. KoLTHOFF and G. H. Bendix (1939) Industr. Enging. Chem. Anal. 11, 94. 



R. Pulver, and F. Verzar (1940) Helv. Chim. Acta, 23, 1087. 



A. WiNKEL and H. Maas (1936) Angew. Chem. 49, 827. 



Comment on papers 95, 96 



Uptake of phosphate into fermenting yeast cells was found under the conditions 

 of the experiment to be an almost one-sided process (paper 95). In strongly fer- 

 menting yeast, a full interchange, however, takes place between the potassium 

 of the yeast cells and the potassium of the nutrient solution already in the course 

 of 2 hr. (paper 96). By making use of ^^K and also with ^^V lahehed yeast cells 

 the extrusion rate of potassium and of phosphorus compounds from the yeast 

 cells can conveniently be measured. 



