CHEMISTRY. 329 



showed a rate of hj^drolysis equal to or slightly greater than that 

 observed with the cereal starches, except that results were abnormally 

 low in experiments in which purified pancreatic amylase acted upon 

 highly purified alkali-washed potato starch. In this case, however, the 

 addition of a small amount of boiled, carefully neutraUzed water 

 extract of potato to the digestion mixture resulted in hydrolysis at a 

 fully normal rate. When potato extract was similarly added to dis- 

 persions of the starches which had shown normal digestibility, the 

 rate of hydrolysis was increased slightly, not only in the case of purified 

 pancreatic amylase, but also of commercial pancreatin and of saliva. 

 With the amylases of malt and of Aspergillus oryzce no such effect was 

 observ'ed. 



The probability that the activation of these enzymes by the potato 

 extract was due to the amino acids and acid amids present and the 

 importance, to our research as a whole, of accurate knowledge of each 

 of the factors concerned in the activation of the amylases, led us to take 

 up, at this time, a careful investigation of the effects of typical amino 

 acids upon amylase action. As yet our experiments in this direction 

 have dealt \sdth aspartic acid and asparagin. Like the water extract 

 of potato, neutralized aspartic acid (neutral solution of sodium aspar- 

 tate) corrected the abnormally low results observed when purified 

 pancreatic amylase acted upon potato starch which had been purified 

 by washing wdth very dilute alkaU and subsequent thorough washing 

 with specially purified water. It also increased the rate of hydrolysis 

 of all of the starches studied (wheat, maize, rice, and potato) when the 

 enzyme employed was either purified pancreatic or malt amylase, com- 

 mercial pancreatin, or saliva; but did not increase the activity of a 

 simple extract of malt or of either the commercial or the laboratory 

 preparation from Aspergillus oryzce. Similar results were obtained in 

 experiments in which the enzymes acted upon "soluble" starch pre- 

 pared by the Lintner method and the amount of reducing sugar formed 

 was determined gravimetrically. This latter method of experimenta- 

 tion was also employed in the study of the influence of asparagin. 



The results obtained with asparagin were essentially similar to those 

 described for aspartic acid. Only in the case of taka-diastase was there 

 an apparent slight activation by asparagin and not by aspartic acid, 

 but the difference was very small, possibly within the limits of experi- 

 mental error. 



Many experiments have been carried out with the different enzymes 

 in w^hich both aspartic acid (neutral solution of sodium aspartate) and 

 asparagin were added to the same digestion mixture and in all cases 

 the results have been such as are obtained by the use of an optimum 

 concentration of either of these substances alone. Thus the activating 

 effects of aspartic acid and asparagin are interchangeable rather than 

 additive. 



