PlCROLONATES OF THE MONOAMINO AdDS. I I I 



2. 20 c.c. leucine + NH 4 C1 < 180 c.c; 50 c.c. final filtrate, 

 titration 2.7, theory 2.77. 



3. Mixture of urea, (NH^SO^ uric acid, alanin, glycocoll, 

 glutamic acid (all tested substances), containing 0.144 

 gm. amino-acid nitrogen, yielded by new method 0.132, 

 0.148, 0.143 gm. 



B. Pure Substances added to urines. 



1. 200 c.c. normal urine; 100 c.c. final filtrate, titration 

 9.6 c.c. N/10 NaOH. 



200 c.c. normal urine + 20 c.c. iV/20 leucin; 100 c.c. fil- 

 trate, titration 11.8 NaOH 



Difference 2.2 c.c, theory 2.5 c.c. 



2. 200 c.c. urine of puerperient woman; 100 c.c. filtrate, 

 titration 9.7 N/10 NaOH. 



200 c.c. urine of puerperient woman + 20 c.c. N/10 

 alanin, titration 14.7 N/10 NaOH. 



Difference 5.0 c.c. N/10 NaOH, theory 5.0 c.c. 



79 (688) 



Picrolonates of the monoamino acids. 1 

 By P. A. LEVENE and DONALD D. VAN SLYKE. 



[From the Rockefeller Institute for Medical Research, New York.] 



Picrolonic acid, used by Steudel to precipitate the hexone bases, 

 and later shown by Mayeda to form salts with the aromatic amino 

 acids tryptophane and phenylalanine, also forms crystalline salts 

 of normal composition with the other monoamino acids obtained on 

 hydrolysis of proteins. The salts are made by dissolving molecular 

 proportions of amino acid and picrolonic acid in a minimum 

 amount of boiling water. The picrolonates crystallize from the 

 cooling solutions, usually while they are still warm. In cold water 

 many of them are very insoluble. In alcohol they are all more 

 soluble than in water. Following is a list of the amino acids of 



1 After this title had been sent to the secretary an article by Abderhalden and 

 Weil appeared describing picrolonates of glycocoll; d-alanine, and dl-leucine (Ztschr. 

 physiol. Chem., 78, 150). They were formed in alcoholic solution, which yielded 

 products of abnormal composition in the cases of glycocoll and alanine. 



