168 THE PROTEIN SUBSTANCES. 



2. Chondroproteins. 



Chondroproteins are those glycoproteins which as primary cleav- 

 age products yield protein and an ethereal sulphuric acid containing a 

 carbohydrate, chondroitin-sulphuric acid. Chondromucoid, occurring in 

 cartilage, is the best example of this group. Amyloid occurring under 

 pathological conditions also belongs to this group. On account of the 

 property of chondroitin-sulphuric acid of precipitating protein, it is also 

 possible that under certain circumstances combinations of this acid 

 with protein may be precipitated from the urine and be considered as 

 Chondroproteins. 



The chondromucoid, the so-called tendon-mucin, and the osseomucoid 

 have greatest interest as constituents of cartilage, of the connective 

 tissues, and the bones, and on this account these bodies and their cleavage 

 product, chondroitin-sulphuric acid, will be treated in a following chap- 

 ter (X). On the contrary, amyloid, which has always been considered 

 in connection with the protein substances, will be described here. 



Amyloid, so called by VIRCHOW, is a protein substance appearing 

 under pathological conditions in the internal organs, such as the spleen, 

 liver and kidneys, as infiltrations; and in serous membranes as granules 

 with concentric layers. It probably also occurs as a constituent of 

 certain prostate calculi. The chondroprotein occurring under physio- 

 logical conditions in the walls of the arteries is, perhaps, according to 

 KRAWKOW, very nearly related to the amyloid substance, but not iden- 

 tical with it, as shown by NEUBERG. 1 



Very recently O. HANSSEN 2 has studied the mechanically isolated 

 amyloid obtained from the so-called " sago kernels " of an amyloid spleen, 

 and could not detect any conjugated sulphuric acid in it. According to 

 his investigations true amyloid is not a chondroprotein. On the other 

 hand, he has found that amyloid organs (liver and spleen) are much 

 richer in sulphuric acid that splits off than normal organs, and it is 

 not improbable that the amyloid formation goes hand in hand with the 

 formation of a chondroprotein. The question as to what relation 

 this amyloid investigated by HANSSEN bears to such a chondroprotein 

 and to the substances studied by others and called amyloid, requires 

 further study, and the question as to the nature of the so-called amyloid 

 is still unsettled. The amyloid protein prepared by MAYEDA S did not 

 contain any chondroitin-sulphuric acid. It yielded histidine and did 



1 Krawkow, Arch. f. exp. Path. u. Pharm., 40, which contains the literature; Neu- 

 berg, Verhandl. d. d. Pathol. Gesellsch., 1904. 



2 Biochem. Zeitschr., 13. 



3 Zeitschr. f. physiol. Chem., 58. 



