560 CHEMISTRY OF THE PROTEIDS CHAP. 



C 9 O 3 NH 2 NH 4 , and suggest that the presence of glycocoll in any album- 

 inous compound may readily be determined by oxidising the albumin 

 with boiling calcium permanganate, according to Steudel's method, 

 and then isolating the ammonium oxaminate, for glycocoll gives rise 

 to oxaminic acid, NH 2 . C 2 O 2 . OH, when it is oxidised with perman- 

 ganates. The search for oxaminic acid was suggested by the 

 previous paper of Ehrmann, who, working in Hofmeister's Laboratory, 

 put forward the view that on the strength of Hofmeister's theory as to 

 how amino-acids are linked together, there are formed, by hydrolysis, 

 oxamid J oxaminic acid ^t oxalic acid ^f. ammonia (see p. 243). 

 Seemann found amongst the oxidation products of gelatine, in 

 addition to oxalan and calcium and ammonium oxalate, the following 

 ether-soluble acids : oxalic-, succinic-, benzoic-, formic-, acetic- and 

 butyric-acids, further benzaldehyde, and perhaps also propionic- and 

 valerianic acids. 



Zickgraf, 1 in support of Kossel's view that the biuret - reaction 

 depends on a special way in which arginin-molecules are linked to one 

 another and to the other complexes of the albumin molecule, found on 

 oxidising gelatine with permanganates that the biuret reaction dis- 

 appears at that time when the largest amount of guanidin is found 

 amongst the dissociation - products. As guanidin is derived from 

 arginin, he reasons that some connection must exist between the dis- 

 appearance of the biuret reaction and the maximal yield of guanidin. 

 That this view is not tenable seems to follow from the researches of 

 von Fiirth. 2 ' 



Heating gelatine for four days under pressure gives in the main 

 only rise to albumoses, according to Nasse 3 and Framm. 4 



The absence of tyrosin and tryptophane amongst the dissociation- 

 products and the high percentage of glycocoll show that gelatine 

 belongs exclusively to the antigroup of the albumin-molecule (see index 

 under antigroup). It behaves also towards enzymes exactly like a 

 hetero-albumose. Trypsin, according to the older observations of 

 Nencki, 5 Tatarinoff, 6 Kiihne, 7 and Reich-Herzberge, 8 gives rise to no 



1 G. Zickgraf, Inaugural Dissertation. Marburg, 1904 ; Zeitschr. f.physiol. Chew. 

 41. 259 (1904). 



2 Otto v. Fiirth, Hofmeister's Beitrdge, 6. 296 (1905). 



3 0. Nasse and A. Kriiger, Naturf. Gesellsch. zu Rostock, Rostocker Ztg. 1889, 

 Nr. 105 (reprint). 



4 F. Framrn, Pftuger's Archivf. <L ges. Physiol. 68. 144 (1897). 



5 M. Nencki, Ber. d. deutsch. chem. Ges. 7. II. 1593 (1874) ; L. Selitrenny, 

 Monats.f. Chem. 10. 908 (1889). 



6 P. Tatarinoff, Zentralbl. f. die medizin. Wissensch. 1877, p. 275.- 



7 W. Kiihne, Verh. d. Heidelberger Naturhist.-med. Verein, N.F. I. p. 194 (1876). 



8 F. Eeich-Herzberge, Zeitschr. /. physio? . Chem. 34. 119 (1901). 



