354 CARNEGIE INSTITUTION OF WASHINGTON. 



ment, three products in each year showing powers between 1,450 and 

 1,570, new scale, corresponding to 2,200 and 2,350 on Lintner's scale. 

 This marked similarity of power among the six most active preparations 

 acquires additional significance from the fact that they were obtained 

 from four kinds of material — green malt, pale kiln-dried malt, and two 

 malt extracts which had been prepared and concentrated on a com- 

 mercial scale, but by somewhat different methods. That a marked 

 advance in the average activity of our product did not reveal any 

 increase in the maximum power observed during the previous year, 

 and that the best preparations obtained from different materials and 

 by somewhat different methods show such striking uniformity in dia- 

 static power, suggests that these preparations may be regarded as a 

 fairlj' definite product approximating the maximum activity obtainable 

 in malt amylase. 



Some of the properties of this product were described in our report 

 of last year (and more fully in the Journal of the American Chemical 

 Society, October and November 1913), from observations upon the 

 preparations of high activity obtained in 1912-13. The additional 

 data determined during the past year are again in harmony with 

 Osborne's view as to the chemical nature of this enzyme and in opposi- 

 tion to those of Frankel and Hamburg and of Pribram. 



The amylase of malt and that of the pancreas are found to be very 

 similar in their chemical nature, as show^n by their qualitative reactions, 

 the percentage of nitrogen which they contain, and the distribution of 

 this nitrogen among the different types of amino-acid radicals present. 

 That they are nevertheless quite distinct substances appears to be 

 established by certain pronounced differences in their behavior. It 

 is found, for example, that malt amylase is much the more stable in 

 pure water solution, while pancreatic amylase is the more stable in 50 

 per cent alcohol and remains active much longer than the malt amylase 

 when allowed to act upon starch. Moreover, the amylase of malt 

 shows its optimum activity in a slightly acid medium, that of the pan- 

 creas in a slightly alkaline medium. 



In our earlier work upon malt amylase it appeared to be but little 

 influenced by the addition of electrolytes; but as purer preparations of 

 the malt enzyme were obtained, the necessity for activation by electro- 

 lytes became strikingly demonstrable. Malt amylase preparation No. 

 118, for example, which, when tested with the usual small addition of 

 potassium acid phosphate, showed an activity of 1,340, new scale, 

 equivalent to 2,000 on Lintner's scale, was practically inactive when 

 tested upon purified starch in redistilled water. During the past 

 year much time has been devoted to experiments upon the influence of 

 activators. 



Since malt amylase is most active in a slightly acid medium, we have 

 given attention first to acid substances. The optimum activation by 



