CARBOHYDRATE MOIETY OF THE PROTEINS. 83 



benzoic acid, and other bodies. With aqua regia, fumaric acid, oxalic acid, chlor- 

 azol, and other bodies are obtained. The investigations of HABERMANN and 

 EHRENFELD and PANZER 1 upon the action of chlorine upon proteins and 

 closely related products are important. 



By the dry distillation of proteins we obtain a large number of decomposition 

 products having a disagreeable burnt odor, and a porous glistening mass of carbon 

 containing nitrogen is left as a residue. The products of distillation are partly 

 an alkaline liquid which contains ammonium carbonate and acetate, ammonium 

 sulphide, ammonium cyanide, an inflammable oil, and other bodies, and a brown 

 oil which contains hydrocarbons, nitrogenized bases belonging to the aniline and 

 pyridine series, and a number of unknown substances. 



The occurrence of protein substances which contain a carbohydrate 

 group has been known for a long time. The nature of this carbohydrate, 

 which can be split off by acid and which may amount to as much as 35 

 per cent, has been explained chiefly by the investigations of FRIEDRICH 

 MuLLER 2 and his students. They have shown that it is always an 

 ammo-sugar, and generally glucosamine. That so-called true proteins 

 also yield a carbohydrate on hydrolytic cleavage was first shown by 

 PAVY, using ovalbumin. The continued investigations of FR. MULLER, 

 WEYDEMANN, SEEMANN, FRANKEL, HOFMEISTER, and LANGSTEIN S 

 have demonstrated that in these cases the carbohydrate is also glucos- 

 amine. A carbohydrate complex, although sometimes only to a very 

 slight amount, has also been detected in other proteins, ovoglobulin, 

 serglobulin, seralbumin, peaglobulin, albumin of the gramineae, yolk- 

 proteid, and fibrin. In other proteins, on the contrary, such as edestin 

 (of the hemp-seed) and casein, myosin, pure fibrinogen, end ovovitellin, 

 carbohydrates have been sought for with negative results. All proteins 

 hence do not contain a carbohydrate group, and future investigators 

 must therefore decide whether the carbohydrate groups belong positively 

 to the protein complex or whether they are united with the protein only 

 as impurities. Several observations 4 show that in working with crys- 

 talline proteins a contamination with other protein substances is unfor- 

 tunately not excluded, and this must not be lost sight of, especially as 

 the quantity of carbohydrates obtained is often very small. In the 

 present state of our knowledge we are not warranted in considering the 

 carbohydrate groups as belonging to the carbon nucleus produced on the 

 destruction of the real protein complex. 



1 Habermann and Ehrenfeld, Zeitschr. f. physiol. Chem., 32; Panzer, ibid., 33 and 34. 



2 Midler, Sitzungsber. d. Ges. d. Natuw. zu Marburg, 1896 and 1898, and Zeitschr. 

 f. Biologie, 42. 



3 In regard to the literature on this subject see the work of Fr. Miiller, Zeitschr. 

 f. Biologie, 42, and Langstein, Ergebnisse der Physiologic, Jahrg. I, Abt. 1, 63, Zeitschr. 

 f. physiol. Chem., 41, and Hofmeister's Beitrage, 6. See also Abderhalden, Bergell, 

 and'Dorpinghaus, Zeitschr. f. physiol. Chem., 41. 



4 See Wichmann, Zeitschr. f. physiol. Chem., 27, and N. Schulz, Die Grosse des 

 Eiweissmolekiils, Jena, 1903, 51. 



