334 CARNEGIE INSTITUTION OF WASHINGTON. 



Since the last report nine papers have been published concerning work 

 more or less supported by grants from the Institution. Among these papers 

 are several which nearly complete the publication of recent thermochemical 

 work conducted with these grants. 



Sherman, H. C, Columbia University, New York, N. Y. Chemical 

 Investigation of Amylases and Related Enzymes. (For previous reports 

 see Year Books Nos. 11-20.) 



The experimental study of the influence of amino acids upon the enzymic 

 hydrolysis of starch, which was discussed in the report of last year, has been 

 extended with results which throw additional light upon the chemical nature 

 of the enzyme, and an investigation of the isoelectric points of the amylases 

 has been begun. 



A notable feature of the work as previously reported was the fact that 

 histidine and tryptophane did not increase the amyloclastic activity of the 

 enzyme, as did all of the monoamino acids which we have tested. It was 

 barely conceivable that this might have been due to traces of mercury accom- 

 panying these two amino acids as an impurity through having been used as a 

 reagent in their preparation. This remote possibility has now been disposed 

 of by experiments in which it has been shown that mercury, like copper, does 

 exert a deleterious or inhibitory effect upon the unprotected enzyme; but that 

 the presence of amino acid protects the enzyme from inactivation by mercury, 

 as it does from inactivation by copper. These experiments have been com- 

 pleted and the results prepared for publication. 



On extending the work with the basic amino acids, it has been found that 

 lysine resembles histidine and tryptophane in not increasing the amyloclastic 

 activity of pancreatic amylase, while both lysine and tryptophane do increase 

 its saccharogenic activity. (The effect of histidine upon saccharogenic activity 

 can not be tested in the same way, because its presence interferes with the 

 determination of the sugar formed.) That lysine is without influence upon 

 the amyloclastic action, but does favorably influence the saccharogenic activity 

 of the enzyme, and that tryptophane shows similarly contrasting results when 

 tested for its influence upon these two phases of enzyme activity, are findings 

 which lead to considerations of much theoretical interest. Previous studies 

 of pancreatic amylase have tended to indicate a closer parallelism between the 

 two phases of activity of this enzyme. The quantitative values of the amylo- 

 clastic and saccharogenic powers of different preparations from the pancreas 

 have shown an approximately constant relation to each other. The same 

 concentrations of hydrogen ion and of sodium chloride and disodium phosphate 

 appear to be required for optimum amyloclastic as for optimum saccharogenic 

 activity. When two representative monoamino acids, glycine and phenyl- 

 alanine, were tested for their influence, first upon the saccharogenic and then 

 upon the amyloclastic activity of pancreatic amylase, both substances showed 

 favorable effects in each case. The results obtained with lysine and trypto- 

 phane, however, emphasize the fact that amyloclastic and saccharogenic 

 activity are to some extent different properties of the amylase. If there were 

 no other evidence, these two activities would usually be attributed to the 

 presence of two different enzymes in the amylase preparations used; but the 

 ratio of amyloclastic to saccharogenic activities of the purified amylase prep- 



