PROTEOSES AND PEPTONES. 133 



views of KUHNE are not in all points correct still the fact remains that 

 under certain circumstances the protein can be split into fractions, of which 

 the hemi group is further easily decomposed by enzyme action while the 

 other, the anti group, is very much more resistant to such action. It 

 also seems as if the first group is characterized by a larger content of 

 tyrosine, tryptophane and the latter by its content of glycocoll, phenyl- 

 alanine and proline. 



By the use of the methods specially worked out by the HOFMEISTER 

 school, of fractionally salting out with ammonium sulphate or zinc sul- 

 phate or also by SIEGFRIED'S iron-alum method, numerous attempts to 

 separate the various proteoses and peptones have been made. 1 Not 

 only have we learned by these methods of a larger number of proteoses, 

 but our older conception of the products formed primarily has been 

 materially modified. Immediately at the commencement of diges- 

 tion, even in peptic digestion, a splitting of the protein molecule into 

 several complexes takes place. In opposition to the view of HuppERT, 2 that 

 the proteoses, in pepsin digestion, are always derived from the primarily 

 formed acid albuminate, PICK and ZTJNZ have shown that several pro- 

 teoses, as well as acid albuminate, appear as primary products at the 

 commencement of the digestion. According to GOLDSCHMIDT 3 a splitting 

 off of proteoses and the formation of acid albuminate takes place simul- 

 taneously by the action of dilute acids alone. Besides the proteoses 

 we also have, according to ZUNZ and PFAUNDLER, even at the beginning, 

 other primary bodies, which cannot be salted out and which do not 

 give the biuret reaction, but are in part precipitated by phosphotungstic 

 acid. These little-known products seem to be intermediate between 

 the peptones and the amino-acids, and they correspond probably to 

 the polypeptide bodies obtained by FISCHER and ABDERHALDEN in tryptic 

 digestion. 



By fractional precipitation of WITTE'S peptone with ammonium sulphate 

 PICK has obtained various chief fractions of proteoses. The first contains the 

 proto- and heteroprpteoses whose precipitation limit lies at 24-42 per cent satu- 

 ration with ammonium sulphate solution, i.e., the presence of 24-42 cc. of the 

 saturated ammonium sulphate solution in 100 cc. of the liquid. Then follows 

 a fraction A at 54-62 per cent saturation, then a third fraction B, with 70-95 

 per cent saturation, and finally fraction C, which precipitates from the saturated 

 solution on acidification with sulphuric acid saturated with the salt. 



1 Umber, Zeitschr. f. physiol. Chem., 25; Alexander, ibid., 25; Pfaundler, ibid., 

 30; Zunz, ibid., 28, and Hofmeister's Beitrage, 2; Pick, ibid., 2, and Zeitschr. f. physioL 

 Chem., 24 and 28; Siegfried, see footnote 3, p. 136. 



2 Schiitz and Huppert, Pfliiger's Arch., 80. 



* F. Goldschmidt, Ueber die Einwirkung von Sauren auf Eiweisstoffe, Inaug.- 

 Diss. Strassburg, 1898. 



