602 VEGETABLE ENZYMES. XIX 



enough data were obtained to calculate the velocity constants satisfac- 

 torily, assuming that such constants would be obtained. In order to 

 determine the different times for the same action, further assumptions 

 would have to be introduced. The hydrogen ion concentrations of 

 the solutions did not change during the actions. 



The amounts of sucrase action with the same quantity of enzyme 

 material at different intervals of time were studied. The results are 

 given in terms of mg. of CuoO obtained, calculated back to 1 cc. of 

 original extract with 2.5 and 5 per cent sucrose solutions. The 

 hydrogen ion concentration was that of the natural juice, not far 

 removed from the optimum. 



Time (hrs.) 1 2 3 4 5 6 24 



2 . 5 per cent sucrose solution 65 134 210 224 228 218 230 



5.0 " " " " 72 150 226 319 394 395 393 



These results are shown graphically in Fig. 2. The one point at 

 6 hours with 2.5 per cent sucrose solution is evidently incorrect. 

 The experimental errors are magnified by the calculations, since the 

 difference indicated by 228 and 218 was caused by a difference in the 

 weighings of 2.3 mg. of CuoO. 



These results bring out the following facts. The action is a linear 

 function of the time, the amounts hydrolyzed being proportional 

 to the time of action until practically all the sucrose was hydrolyzed." 

 The action with 5 per cent sucrose solution was only slightly greater 

 than with the 2.5 per cent solution, indicating that the sucrase was 

 nearly saturated in the more dilute solution. However, the total 

 action for the more concentrated solution was not twice as large as 

 for the dilute solution in the limited times used. The products of the 

 reaction evidently played a part here, interfering with the action of 

 the sucrase. These results are similar to those obtained in the more 

 extended investigations of yeast sucrase by others. 



Active precipitates were obtained by the addition of alcohol or of 

 acetone to the sucrase solution. These did not form clear solutions 

 again, but showed considerable actions when tested as suspensions. 



" Similar relations within certain limits have been observed with yeast sucrase. 

 Nelson, J. M., and Vosburgh, W. C, J. Am. Chem. Soc, 1917, xxxix, 790. Mi- 

 chaelis and Rothstein.^° 



