338 CARNEGIE INSTITUTION OF WASHINGTON. 



the problem of adsorption. As a preliminary step, he has developed 

 an apparatus for measuring small pressures which is sensitive to within 

 0.0003 mm. Although this research does not come under the head 

 of researches primarily subsidized by the Caniegie Institution of Wash- 

 ington, and its main expenses are defrayed from another source, 

 nevertheless the apparatus which he has devised may be of great use 

 in those researches. Moreover, he has been given the temporary use 

 of some instruments belonging to the Carnegie Institution of Washing- 

 ton and therefore this research also, when it is completed, will be in 

 some measure indebted to the Institution for assistance. 



A number of papers concerning earlier researches have been pub- 

 lished during the year. These will be found listed in the bibliography. 



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

 tiqation of amylases and related enzymes. (For previous reports see Year 

 Books Nos. 11-18.) 



During the past 12 months the studies of proteolytic activities of 

 our purified pancreatic amylase preparations and related products re- 

 ferred to in the report for 1918 have been completed, and the investi- 

 gation of the influence of amino acids upon the activity of amylases, 

 briefly outlined in our report of last year, has been continued. 



Two papers relating to purification experiments have been prepared. 

 One of these, dealing chiefly with the proteolytic activities of our pan- 

 creatic amylase preparations and related products, has been published 

 in the Journal of the American Chemical Society. The other, describing 

 a more detailed study of certain phases of the purification process, is 

 now in press for publication in the same journal. 



Experiments on the influence of aspartic acid and asparagin upon the 

 activities of several amylases, in natural and in purified form, described 

 in outline in our report of last year, were published in the Journal of 

 the American Chemical Society for November 1919, and the study of 

 the effects of amino acids upon the enzymic hydrolysis of starch has 

 now been extended to glycine, alanine, phenylabinine, and tyrosine. 

 In all of these cases the method of experiment has been to allow the 

 enzyme to act for 30 minutes at 40° upon ''soluble" starch (prepared 

 by the Lintner method) in the presence of optmium concentrations of 

 sodium chloride and of primary or secondary phosphate, with or with- 

 out the addition of the amino acid whose influence is to be tested, 

 and then to measure the extent of the enzymic hydrolysis of the starch 

 by determining the amount of reducing sugar which has been formed. 

 This reducing sugar is chiefly maltose; but since small amounts of glu- 

 cose may also be present, the results are often stated in terms of the 

 weight of cuprous oxide reduced by the sugar or sugars formed. When 

 such amounts of enzyme were used as to result in yields of 200 to 300 

 mg. of cuprous oxide, the increases (in milligi-ams) resulting from the 



