ENERGY SUPPLY OF THE CELL 131 



crepancy that the temperature law of enzymes does not 

 apply to living cells. 



All enzjnues deteriorate, even at low temperatures. 

 Endogenous catabolism in all living cells (p. 16) is 

 almost certainly due in part to deterioration of enzymes 

 in the cell. In normally nourished cells, deterioration 

 probably takes place at the same rate and by the same 

 processes as outside, but new enzyme is being formed 

 continuously to keep a fairly constant enzyme concen- 

 tration in the cell. 



Deterioration will proceed with greater speed at higher 

 temperatures, and as far as enzymes are concerned, we 

 know that their temperature coefficient of deterioration 

 is enormously high. The production of new enzyme 

 in the cell will also be accelerated by a temperature 

 increase, but its temperature coefficient will be normal, 

 i.e., low. In a fermenting liquid heated slowly, the 

 enzymes deteriorate more rapidly, and are likewise 

 being formed more rapidly. There must always be a 

 temperature at which the originally very slow rate of 

 deterioration overtakes the rate of reconstruction. 



Heating above this temperature must cause a gradual 

 decrease of the enzyme content of the cell. The higher 

 it rises, the greater will be the difference between the 

 rate of deterioration and the rate of reconstruction, 

 the quicker will be the decrease of enzyme in the cell. 

 If the rate of deterioration is only slightly greater 

 than that of reconstruction, the cell may come to a 

 constant enzyme concentration below normal, but if the 

 difference is considerable, the enzyme will soon be 

 completely deteriorated. Because of the great difference 

 in temperature coefficients, an increase of only a few 

 degrees will change a rapidly fermenting culture into 

 one that has lost the power of fermentation altogether. 



