336 CHEMISTRY OF THE PROTEIDS CHAP. 



DISSOCIATION OF ALBUMIN BY MEANS OF ACIDS AND ALKALIES 



Acid-Albumins and Alkali- Albuminates 



The dissociation of albumin by means of alkalies and acids is 

 closely related to coagulation, as the albumin is changed primarily 

 into an alkali-albuminate or into an acid-albumin, but sooner or later 

 there are also formed albumoses and peptones. Goldschmidt, 1 Zunz, 2 

 and others have taken the possibility into consideration, that the acid- 

 albumin-moiety corresponds only to one part of the albumin-molecule, 

 and that during its formation the albumose-complexes are separated 

 off. This view is, however, not supported by the fact that the whole 

 of the albumin is converted into acid-albumin on being boiled for a 

 short time with acids (Erb 3 ) ; a second objection is that the ratio of 

 acid-albumin to albumose varies greatly. Acid-albumin is, without 

 doubt, the primary transformation-product of the entire albumin- 

 molecule, while the other products are only formed secondarily, after 

 the lapse of more or less time. 



As already stated on p. 148, so here again we meet with a differ- 

 ence between the readily dissociable hemi-group and the resistant 

 anti-group, and we find that acid-albumin is identical with the anti- 

 albumid coagulum, with plastein, etc. The acid-albumin of the whole 

 albumin-molecule, and the acid-albumin prepared from the anti-group, 

 agree with one another in every particular as regards such external 

 characters as solubility and precipitability, although they differ from 

 one another in their chemical configuration. 



Acid-albumin is formed instantly, whenever a solution of an 

 albumin is heated to its coagulation-temperature in the presence of 

 even the minutest trace of an acid. At room-temperature or at body- 

 temperature this change requires, however, much more time, and also 

 a much more concentrated acid ; in this respect different albumins 

 behave very differently : serum-albumin has been investigated by 

 Johannsson ; 4 serum- and egg-albumin by Goldschmidt ; the muscle- 

 albumins by Kiilme, 5 and by v. Fiirth. 6 The myogen of v. Fiirth is 

 so readily converted into acid-albumin by one drop of a ^ normal 



1 F. Goldschmidt, Sduren und Eiweiss, Dissertation, Strassburg, 1898. 



2 E. Zunz, Zeitschr.f. physiol. Ohem. 28. 132 (1899). 



3 W. Erb, Zeitschr. f. Biol. 41. 309 (1901). 



4 J. E. Johannsson, Zeitschr.f. physiol. Ohem. 9. 310 (1885). 



5 W. Kiihne, Protoplasma und Kontraktilitat, Leipzig, 1864. 



6 O. v. Fiirth, Arch.f. experiment. Pathol. u. Pharmakol. 36. 231 (1895). 



