SOME AUXOAMYLASES 37 



SOME AUXOAMYLASES. 



(ABSTRACT.) 



ELBERT W. ROCKWOOD. 



The amylases, or starch splitting enzymes, are aided, or have 

 their activity increased, by certain nitrogenous compounds par- 

 ticularly those which contain the NH 2 group. These amylolytic 

 stimulating substances I have called auxoamylases. All amino 

 compounds are not auxo substances, however. The experiments 

 described here have been made to ascertain what compounds do 

 activate the amylases and the conditions which affect their 

 action. 



Method. — Boiled starch solution was digested at 38° with dilute 

 enzyme solutions under toluene, portions being removed at in- 

 tervals for testing. The degree of hydrolysis was determined 

 by heating the digested solution on a steam bath with an excess 

 of Fehling's solution, filtering off the cuprous oxide formed, dis- 

 solving this washed precipitate in nitric acid, boiling off the 

 nitrous acid, neutralizing the excess of acid, making acid with 

 acetic acid and precipitating the copper as CuCl with KI. The 

 iodine thus liberated was determined by titration with tenth- 

 normal Na,S 2 3 solution. The quantity of reducing sugar 

 formed by digestion of the starch is, consequently, proportional 

 to the Na,S 2 3 used. Since the hydrogen ion has a marked effect 

 on amylases, when the amino compounds had an acid reaction 

 they were carefully neutralized before the digestion. 



The following classification of the nitrogen compounds was 

 found : 



AUXOAMYLASES. 



Glycine, NH 2 CH 2 C0 2 H. 

 Tyrosine, HOC 6 H 1 CH 2 CH(NH 2 )CO,H. 

 Hippuric acid, QH.CONHCH.CO.H. 

 Anthranilie acid, NH 2 C 6 H 4 C0 2 H. 

 Asparagin, NH 2 COCH 2 CH(NH 2 )C0 2 H. 



INACTIVE NH 2 COMPOUNDS. 



Sulphanilic acid, NH 2 C 6 H 4 S0 3 H. 

 Acid amids like, 



Urea, (NH,>)=CO. 



Acetamid, CH 3 CONH 2 . 



Propionamid, CH a CH 2 CONH 2 . 



