CHEMISTRY. 335 



arations remains practically the same as in the original pancreatin from 

 which they are made, and it appears improbable that two distinct enzymes 

 would pass through the various operations of the purification process without 

 change in their quantitative relations to each other. Of particular interest is 

 the fact that it is the first (amyloclastic) phase of the enzyme's activity which 

 is not influenced by lysine and tryptophane, while the later (saccharogenic) 

 phase is favorably affected. This, interpreted according to the theory out- 

 lined in our report of last year, is an indication that the lysine and tryptophane 

 radicles of the enzjnne molecule are so bound therein as not to be liberated by 

 hydrolysis until after the enzyme has passed the amyloclastic stage of its 

 action, which is a property having to do with the earliest phase of the starch 

 hydrolysis; whereas the saccharogenic activity is chiefly exerted later, and in 

 this later phase of its activity the enzyme (which may have already lost its 

 amyloclastic power) is to a measureable extent protected by the presence of 

 added lysine or tryptophane from such further hydrolytic change as would 

 result in the loss of its saccharogenic activity. The work with lysine has been 

 completed and the results prepared for publication. 



As mentioned in the report of last year, an earlier explanation, chiefly due 

 to Rockwood, of the favorable effect of amino acids upon the activity of 

 amylases, is that they exert a direct activating influence by virtue of the 

 chemical groupings which they contain. If this were the case, similar group- 

 ings in other organic compounds should also show favorable effects when tested 

 upon the enzyme under the same conditions. In order to test this question, 

 a careful study of several types of pure organic compounds has been made. 

 Aniline, methyl- and ethyl-amines, benzoic acid, benzamide, and anthranilic 

 acid collectively contain the amino group and the carboxyl group both singly 

 and in different combinations, but none of these substances showed a favorable 

 influence upon salivary or pancreatic amylase, when tested under standard 

 conditions in the presence of optimum concentrations of hydrogen ion and of 

 sodium chloride and disodium phosphate. Our knowledge of the structure 

 of protein molecules is not sufficiently complete to enable us to select for test 

 any simple a-amino acid with assurance that it is not a possible product of 

 protein hydrolysis; but if the a-amino acid grouping is of itself the cause of the 

 favorable influence of glycine, for example, it would appear that the same 

 property should be shown by hippuric acid (benzoyl-glycine), especially since 

 the benzoyl group has in other experiments been found to be without effect. 

 Hippuric acid, however, when tested under standard conditions, failed to show 

 any favorable influence. The net result of a large number of experiments, 

 which we have made with carefully selected substances, is that they fail to 

 furnish any support for the view that certain organic groupings as such 

 activate amylolytic action. 



On the other hand, the theory that the enzyme molecule, or an essential part 

 of it, is of a protein natiu-e, subject to hydrolysis into amino acids in the 

 aqueous dispersions in which it acts, and therefore capable of being better 

 preserved by the addition of a suitable amino acid to its dispersion medium, is 

 supported both by the experiments with lysine and tryptophane above 

 mentioned and by further experiments in which the effect of certain amino 

 acids upon the deterioration of pancreatic amylase in solution has been tested 

 directly. The extent of the deterioration of this enzyme when allowed to 



