242 CHEMISTRY OF THE PROTEIDS CHAP. 



water. The esters are readily soluble in chloroform ; all traces of 

 water were removed with freshly calcined CuS0 4 , and the esters 

 precipitated from the chloroform solution with ether. These esters 

 are light-brown light powders, readily soluble in alcohol, acetone, 

 chloroform, glacial acetic acid, hardly soluble in ether and petroleum- 

 ether, and quite insoluble in water. 



The esters are very readily saponified with NOH, but only 

 very slowly by boiling water. Warm ammonia was used for this 

 saponification, which might change - COOC 2 H 5 groups into - CONH 2 

 compounds. 



On being boiled for several hours with baryta water the peroxy- 

 proteic acids lose all the oxalic-acid groups (totalling nearly J of the 

 molecule) and the basic complexes, and also a considerable portion oi 

 N. The resulting biuret-compounds are called desamino-proteic acids. 

 These, by hydrolytic dissociation, give rise to glutaminic acid, leucin, 

 benzoic acid, and ammonia. 



While peroxyproteic acids in an alkaline solution are not attacked by 

 KMn0 4 , or only to a slight extent, the desamino-proteic acids are readily 

 attacked, and by further oxidation give rise to kyro-proteic acids, which 

 contain about half the nitrogen in loose, acid-amide combination. On 

 treatment with nitrous acid they yield about ten times more N than 

 is obtained from casein. 



The gradual dissociation of the albumin-molecule is readily seen 

 by comparing the mean percentage composition of the acids formed by 

 oxidation and the ratios of the oxygen to the nitrogen : 



C H N IN: 



Casein . . . 53'0 7'0 157 22'65 1 : 1'25 

 Maly's oxyprot- sul- 

 phonic acid. . 51-21 6-89 14-59 25'54 1 : 1'53 

 Peroxyproteic acids 



AandB . . 45'74 6'08 13'97 33'06 1 : 2'07 



Kyro-proteic acid A 42'24 6'42 11-08 38*68 1 : 3'06 



Peroxyproteic acid B 42'33 5'SS 8*96 41'80 1 : 4'08 



Desamino-proteic acid and kyro-proteic acid are only collective 

 names, to be used in the same sense as " albumose " or " peptone." 



When peroxyproteic acids A and C are converted into desamino- 

 proteic acids they lose all their oxalic-acid radicals, amounting to J 

 of their total weight, and simultaneously nearly J of the total N is 

 lost as NH 3 . As peroxyproteic acid A contains only 6 per cent of its N 

 in loose combination, it is not only the acid-amide N which is eliminated 

 during the formation of desamino-proteic acid. 



