18 STUDIES IN PLANT RESPIRATION AND PHOTOSYNTHESIS. 



Furthermore, while fructose fed to mature leaves showed relatively 

 high respiratory activity, we were surprised to find that the respir- 

 atory activity of the leaves fed fructose was apparently depressed 

 when amino-acids were also given. 



A more encouraging possibility for an explanation of the stimula- 

 tory action of amino-acids was offered by the consideration of the 

 influence of these substances on enzyme activity. That some amino 

 acids have a decided effect on the rate of activity of certain enzymes 

 has been known for a long time. Effront^ in 1893 reported that 

 asparagine accelerates the hydrolysis of starch by takadiastase and 

 later^ showed that this accelerating action was also accomplished 

 by other amino-acids, while amines and their salts and acid amides 

 and their salts showed no such action. 



The observation that the saccharification of starch by pancreatic 

 juice was accelerated by amino-acids was reported by Terroine 

 and Weill. ^ Even very low concentration of gylcocoll, 1:10,000, 

 increases the velocity of the saccharification 30 to 40 times. Dakin^ 

 observed that many condensations which have their analogues in 

 the metabolism of living organisms are induced by amino-acids, 

 peptones, albuminose, and some proteins, while the same reactions 

 do not take place without these substances. Jacoby and Umeda^ 

 also observed that the activity of soja-urease is greatly accelerated 

 by glycocoll, anahne, tyrosine, leucin, and glutamic acid. The 

 activity of pine diastase was investigated by Ujhara," who found 

 that this action was increased 48.5 per cent by very small quantities 

 of glutamic acid and by glycocoll 45.1 per cent. Similar results were 

 obtained with dog-serum diastase. Sherman and Walker^ have 

 subjected the accelerating action of amino-acids on diastase to thor- 

 ough investigation. They have found the acceleration to take place 

 with diastase derived from a variety of sources as well as with starches 

 of widely different origin. Also, the acceleration is not due to any 

 change in the hydrogen-ion concentration nor to a more favorable 

 concentration of the electrolytes. 



Finally, Burge^ has investigated the influence of introducing 

 various amino-acids into the intestine and stomach on the catalase 

 activity of the blood. While this is stimulated apparently by a 

 large variety of substances, it would seem that the amino-acids 



» Effront, I. Mon. Sci., 41, 266 (1893). 



* Idem. Ibid., (4), 18, 561 (1904). 



» Terroine, E., and J. Weill. Chem. Abstracts, 4, 1535 (1913). 



* Dakin, H. D. Jour. Biol. Chem., 7, 49-55 (1910). 



* Jacoby, M., and N. Umeda. Biochem. Zeitschr., 68, 23-47 (1918). 

 « Ujhara, K. Chem. Abstracts, 12, 1971 (1918). 



' Sherman, H. C, and Florence Walker. Influence of aspartic acid and asparagine upon the 

 enzymatic hydrolysis of starch. Jour. Amer. Chem. Soc, 41, 1866-1873 (1919); 43, 2461- 

 2476 (1921). 



«Burqe, W. E. Amer. Jour. Physiol., 47, 351-355 (1918); 48, 133-140 (1919); Science, n. s., 

 49, 594-595 (1919). 



