848 15. EFFECTS OF VARIOUS FACTORS ON INHIBITION 



et al., 1948). These curves demonstrate well that the effect of pressure can 

 vary with the temperature; high pressure reduces the inhibition below 

 18° and above 47°, but increases it between these temperatures. Similar 

 variations would probably be seen with changes in the pH, since the pres- 

 sure effect on the uninhibited rate is pH-dependent. It may be noted that 



Fig. 15-24. Effects of temperature and pressure on the inhi- 

 bition of yeast ^-fruetofuranosidase by urethane (500 mM). 

 A, 1 atm pressure and B, 680 atm pressure. (From Johnson 

 et al, 1948.) 



at all temperatures an increase in the pressure accelerates the rate, whether 

 urethane is present or not. The effect of urethane doesn't change with pres- 

 sure markedly up to 45° but above this temperature the inhibition is 

 mainly suppressed. Calculations of the volume changes indicated that in 

 the lower temperature range there is a decrease in the volume (around 



