356 CARNEGIE INSTITUTION OF WASHINGTON. 



Sherman, H. C, Columbia University, New York, New York. Continuation 

 of the chemical investigation of the amylases. (For previous reports see 

 Year Books Nos. 11-14.) 



During the past year the investigations, referred to in previous 

 reports, upon the chemical properties of three typical amylases of 

 widely different biological origin, have been continued, chiefly through 

 detailed quantitative studies of the reactions induced by these enzymes 

 and of the conditions most favorable to their action. 



In the study of pancreatic amylase attention has been directed 

 especially to the determination of the optimum hydrogen ion concen- 

 tration and to the measurement of proteolytic activity. Determina- 

 tion of the exact alkalinity at which this enzyme show^s its greatest 

 amylolytic power is especially difficult because of the extreme sensi- 

 tiveness and instability of its solutions. The results thus far obtained 

 show that the region of optimum activity is not so sharply limited as 

 in the case of malt amylase reported last year. The greatest 

 activity of the malt enzyme, whether activated by strong or weak 

 acid or by acid salt, was found always at Ph"*" 4.4 (within hmits of 

 experimental error of measurement of hydrogen-ion concentration) ; but 

 the pancreatic amylase in solutions activated by chloride and phos- 

 phate shows optimum activity (within limits of error in measuring 

 the diastatic power) throughout the range of Pr"^ 7.0 to 7.6. Using 

 carbonate instead of phosphate as alkahne activator, the quantities 

 resulting in optimum activity have been determined experimentally 

 and the hydrogen ion concentrations of these solutions are now being 

 measured. In connection with these figures we would note that 

 highly purified water, such as was used in these experiments, or water 

 containing only a minimum addition of neutral salt, showed (as 

 pointed out by Fales and Nelson and repeatedly confirmed in our 

 work) an index of 5.6 to 6.2. 



The systematic investigation of proteolytic activity in our pan- 

 creatic amylase preparations necessitated first a careful study and 

 adaptation of several methods for detecting and measuring prote- 

 olysis. This study has now been completed and the data prepared 

 for publication. While space does not permit discussion of these 

 results, it may be noted that the quantitative methods, and especially 

 those based upon the measurement of the total nitrogen or amino 

 nitrogen of digestion products, which are best adapted on theoret- 

 ical grounds to the purposes of our investigation, can be made quite 

 as delicate as the merely qualitative tests for products of proteolytic 

 activity. 



Using the quantitative methods thus developed, we have carried 

 on during the year a somewhat extended series of measurements of 

 the proteolytic activity, previously noted as an unexpected property 

 of our purified pancreatic amylase preparations. Whether measured 



