170 THE PROTEIN SUBSTANCES. 



Amyloid gives the xanthoproteic reaction and the reactions of MIL- 

 LON and ADAMKIEWICZ. Its most important property is its behavior 

 with certain coloring matters. It is colored reddish brown or a dingy 

 violet by iodine; a violet or blue by iodine and sulphuric acid; red by 

 methylaniline iodide, especially on the addition of acetic acid; and red 

 also by aniline green. Of these color reactions those with aniline dyes 

 are the most important. The iodine reaction appears less constant and 

 is greatly dependent upon the physical condition of the amyloid. The 

 color reactions are due to the presence of the chondroitin-sulphuric acid 

 component, but this stands in opposition to the behavior of the amyloid 

 obtained by HANSSEN from the " sago " spleen. 



Amyloid may be prepared as follows, according to MODRZEJEWSKI 

 and KRAWKOW. 1 The finely divided organ is exhausted first with water 

 and then with dilute ammonia, which leaves the insoluble amyloid and 

 removes the free or the combined chondroitin-sulphuric acid, besides 

 other substances. The product, after being washed with water, is 

 digested with pepsin for several days at 38 C. The residue, after wash- 

 ing with hydrochloric acid and water, is dissolved in dilute ammonia, 

 filtered, again precipitated with dilute hydrochloric acid, dissolved, if 

 necessary, in ammonia, precipitated a second time with hydrochloric 

 acid, washed with water, the precipitate dissolved in baryta-water, which 

 leaves the nucleins undissolved, and the barium filtrate precipitated 

 with hydrochloric acid, and then washed with water, alcohol, and ether. 



Phosphoglycoproteins. This group includes the phosphorized glycoproteins. 

 They yield no purine bases (nuclein bases) as cleavage products. They are not 

 nucleoproteins and therefore they must not be mistaken for them. On pepsin 

 digestion they may, like certain nucleoalbumins, yield pseudonuclein, but they 

 differ from the nucleoalbumins in that they yield a reducing substance on boil- 

 ing with dilute acid. They differ from the nucleoproteins, which also yield reduc- 

 ing carbohydrates, in, as above stated, not yielding any purine bases. 



Only two phosphorized glycoproteins are known at the present time, namely, 

 ichthulin, occurring in carp eggs and studied by WALTER, 2 and which was con- 

 sidered as a vitellin for a time. Ichthulin has the following composition: C 53.52; 

 H 7.71; N 15.64; S 0.41; P 0.43; Fe 0.10 per cent. In regard to solubilities it 

 is similar to a globulin. WALTER has prepared a reducing substance from the 

 pseudonuclein of ichthulin which gave a highly crystalline compound with phenyl- 

 hydrazine. 



Another phosphoglycoprotein is helicoproteid, obtained by HAMMARSTEN 3 

 from the glands of the snail Helix pomatia. It has the following composition: 

 C 46.99; H6.78; N 6.08; S0.62; P 0.47 per cent. It is converted into a gummy, 

 levorotatory carbohydrate, called animal sinistrin, by the action of alkalies. 

 On boiling with an acid it yields a dextrorotatory reducing substance. 



The compound protein found by SHULTZ and DITTHORN 4 in the spawn of 

 the frog probably belongs to this group, but instead of glucosamine it gives 

 galactosamine on cleavage. 



1 Modrzejewski, Arch. f. exp. Path. u. Pharm., 1; Krawkow, 1. c. 



2 Zeitschr. f. physiol. Chem., 15. 



3 Hammarsten, Pfliiger's Arch., 36. 



4 Zeitschr. f. physiol. Chem., 29. 



