270 LECTURE XII. 



first of all between an oxy-proteinic acid and an alloxy-proteinic acid. 

 Antoxy-proteinic acid has recently been added to these. All three acids 

 contain sulphur, nitrogen, and large amounts of oxygen. 



The following figures will give some idea of their composition. The 

 antoxy-proteinic acid contains 43.21 per cent C, 4 . 91 per cent H, 24 . 40 per 

 cent N, 0.61 per cent S, and 26.33 per cent O; the oxy-proteinic acid 39 . 62 

 per cent C, 5.64 per cent H, 18.08 per cent N, 1 . 12 per cent S, and 35.54 

 per cent 0; and the alloxy-proteinic acid 41.33 per cent C, 5.70 per cent 

 H, 13.55 per cent N, 2.19 per cent S, and 37.23 per cent O. We must 

 also add that O. Thiele * has described a uroferric acid occurring in urine, 

 which undoubtedly belongs to this group of compounds. By heating it 

 with hydrochloric acid in a sealed tube it decomposes, producing melanin 

 substances, carbon dioxide, ammonia, organic sulphur compounds, hydro- 

 gen sulphide, and aspartic acid. We must also add that these substances 

 do not give any albumin reactions. The biuret test, Millon's reaction, 

 and the remaining characteristic test for albumins and their closely- 

 related cleavage-products, all give negative results. We must content our- 

 selves for the present with the mere enumeration of these substances. It 

 is possible that perhaps some light is thrown upon the formation of them 

 by the fact that a difficultly-dialyzable body containing no amino acids 2 

 may be 'isolated from urine, in the same way as alloxy-proteinic acid 

 and oxy-proteinic acid were obtained. Such acids may, however, be 

 obtained from this substance by boiling it with concentrated hydrochloric 

 acid. Glycocoll, leucine, and glutamic acid are then isolated, and the 

 presence of phenyl-alanine and aspartic acid indicated. The substance 

 did not contain any tyrosine. It is very probable that this product is 

 a residue of a partially disintegrated albumin molecule, which has escaped 

 further disintegration. We know nothing further about its relations with 

 the other acids just mentioned. 



In the discussion of the decomposition products of tyrosine and phenyl- 

 alanine, we called attention to two hydroxy-acids which occur in the urine 

 during the very rare metabolic disturbance known as alcaptonuria. Alcap- 

 ton was the name which Bodeker 3 gave to a substance which he isolated 

 from the urine of a man afflicted with diabetes. It gave to the urine two 

 distinguishing characteristics. The urine showed a very appreciable reduc- 

 ing power, and had the property of turning dark brown or black, taking on 

 oxygen, when alkali was added. This alcapton has been isolated from 

 urine by M. Wolkow and E. Baumann, 4 and its composition ascertained 



1 O. Thiele: Z. physiol. Chem. 37, 251 (1903). 



2 E. Abderhalden and F. Pregl: ibid, 46, 19 (1905). 



8 Bodeker: Z. rat. Med. 7, 130 (1859); Ann. 17, 98 (1861). 



4 M. Wolkow and E. Baumann: Z. physiol. Chem. 16, 228 (1891). Here are given 

 references to the older literature. 



