336 CARNEGIE INSTITUTION OF WASHINGTON. 



stand in solution for different lengths of time and at different temperatures 

 with and without the addition of amino acid has been determined. It was 

 found, for example, that a solution of pancreatic amylase (containing optimum 

 concentrations of chloride and phosphate) which had stood for one hour at 40° 

 C. showed about one-third greater activity when alanine had been added to 

 the solution in advance. If protection against hydrolytic destruction is an 

 explanation of the increased activity of amylase in the presence of amino acid, 

 it is logical to expect that any condition favoring the hydrolysis of the enzyme 

 molecule, such as a higher temperature or subjection to a given temperature 

 for a longer time, would result in a greater apparent effect from the added 

 amino acid. This has been found to be the case. A series of experiments, in 

 which pancreatic amylase has been allowed to act for periods of 30 and of 60 

 minutes at temperatures ranging from 30° to 75° C. has shown the favorable 

 effect of the amino acid to be greater for the longer period and to increase with 

 rise of temperature up to the point at which coagulation of the enzyme occurs. 

 The results of these latter experiments are now being prepared for publication. 



In view of the strong evidence that our typical amylases are in their chemical 

 composition essentially protein substances, and the growing importance of a 

 knowledge of the isoelectric points in working with such substances, an attempt 

 has been made to work out a method for the determination of isoelectric 

 points of amylases by means of a series of electrophoresis and precipitation 

 experiments. For the preliminary experiments thus far performed a com- 

 mercial malt extract has been used because malt amylase is more stable in 

 water than is pancreatic amylase. These experiments have shown the presence 

 in the extract of inert proteins of widely different isoelectric points, and it is 

 hoped that this work may furnish a basis for improvements in the methods of 

 purifying the enzyme. Having now developed a technique which appears to 

 be suitable for electrophoresis experiments upon materials of the sort with 

 which this investigation deals, we hope to extend this phase of the work 

 actively during the coming year. 



The efficient collaboration of those who shared in these investigations, 

 whether as research assistants or volunteers, is gratefully acknowledged. 



