GLYCURONIC ACID 317 



GLYCURONIC ACID 



Constitution. Glycuronic acid, which was discovered as 

 a product of metabolism in 1878 by M. Jaffe and by O. 

 Schmiedeberg and H. H. Meyer, contemporaneously but in- 

 dependently, and the constitution of which was verified by its 

 synthetic production by Emil Fischer and Piloty, is without 

 doubt a direct oxidation product of grape-sugar : 



GLUCOSE GLYCURONIC ACID 



COH COH 



H.C.OH H.C.OH 



OH.C.H OH.C.H 



H.C.OH H.C.OH 



H.C.OH H.C.OH 



[CH 2 .OH COOH. 



Glycuronic acid in metabolism always appears in the 

 form of conjugated glycuronic acids which are laevorotary, 

 an optical dextrogyration being characteristic of the free 

 glycuronic acid. 



The conjugates are in general of the nature of alcohols 

 or phenols. According to the synthesis by ISTeuberg and 

 Neimann and the discovery that glucoside-splitting fer- 

 ments (like emulsin and kefirlactase) are also capable of 

 splitting conjugated glycuronic acids, there is no room for 

 doubt that in a general way these latter correspond to the 

 glucoside type of Emil Fischer. Starting with the tauto- 

 meric, accessory form of glucose 



CH.OH 



the reaction with an alcohol obviously takes place with 

 separation of water and oxidation of the terminal CH 2 .OH 



