84 



CHEMISTRY OF THE PROTEIDS 



CHAP. 



Its occurrence in egg-white, and the so-called glyco-albumins were first 

 observed by Fr. Mtiller. 1 Glucosamin is, however, according to 

 Steudel 2 and Frankel, 3 not a primary dissociation-product, but is 

 formed secondarily out of a primary product. 



6. Galactosamin takes the place of glucosamin in the mucus 

 forming the covering of frogs' eggs (Schulz and Ditthorn). 4 



7. Kynurenic Acid, C 10 H 7 N0 3 = y-oxy-/2-quinolin-carboxylic 

 acid. 5 Liebig discovered it in the urine of dogs, and Glassner and 

 Langstein 6 have ascertained that, in the body, its mother-substance 

 occurs amongst the alcohol -soluble, acetone -insoluble autodigestion 

 products of the pancreas. After Camps 7 had shown that kynurenic 

 acid was y-oxy-/3-quinolin-carboxylic acid, Ellinger 8 has proved ex- 

 perimentally that feeding dogs with tryptophane, or injecting it in 

 dilute soda solution subcutaneously, leads to an excretion of kynurenic 

 acid. 



Hopkins and Cole have found that tryptophane may be converted 

 into an oxy-quinoline derivative, having the formula C 9 H 7 NO, an 

 observation which Ellinger believes to strengthen his view that 

 kynurenic acid is a derivative of tryptophane, and that tryptophane 

 possesses an arrangement by means of which it is readily converted 

 into a quinoline. Compare with p. 51. 



CH.COOH 



C.COOH 



NH 

 Tryptophane 



becomes 



Kynurenic acid. 



On being heated kynurenic acid is converted into kynurin. 



1 Fr. Miiller, Zeitschr. f. BioL 42. 468 (1901). 



2 H. Steudel, Zeitschr. /. physiol. Chem. 34. 353 (1901). 



3 S. Frankel, Monatshefte f. Chem. 19. 747 (1898). 



4 F. N. Schulz and F. Ditthorn, Zeitschr. f. physiol. Chem. 32. 428 (1901). 



5 For literature see : L. B. Mendel and H. C. Jackson, Americ. Journ. of Physiol. 

 2. 1 (1898) ; A. Josephsohn, Inaugural Dissertation, Konigsberg, 1898. 



6 K. Glassner and L. Langstein, Hofmeisters Beitrdge, II. 34 (1902). 



7 R. Camps, Zeitschr. f. physiol. Chem. 33. 390 (1901). 



8 Alexander Ellinger, ibid. 43. 325 (1904). 



