BENCE-JONES PROTEIN 527 



Sulphur is readily split off by alkalies, reacting with lead acetate to produce 

 lead sulphide (Boston). 



After standinp; in alcohol, by which the protein is precipitated, it loses its solu- 

 bility (differing in this respect from albumose). 



As to the exact nature of this protein, httle can be said at the pre- 

 sent time. Since protoproteoses, dcuteroprotcosos, and peptone are 

 split off on digestion with pepsin, the molecule is evidently larger than 

 that of any of the albumoses. The well-purified substance is free 

 from phosphorus, and hence contains no nucleins; but it contains con- 

 siderable sulphur (between 1 and 2 per cent.), which is readily split 

 off. Like casein, it contains no hetero-group (lack of heteroproteoses 

 on digestion), but differs in containing a carbohydrate group (in small 

 amount) and in the absence of phosphorus. On hydrolysis Magnus- 

 Levj^'-^ obtained glutaminic acid, tyrosine, and leucine, but no glycine. 

 He found the nitrogen distributed as follows: amid-nitrogen, 9.9 

 per cent.; humin-nitrogen, 9.8 per cent.; diamino-nitrogen, 6.4 per 

 cent. — which last was composed of : histidine, 0.9 per cent.; arginine, 

 2.4 per cent.; lysine 3.0 per cent. The extensive analytic studies of 

 Hopkins and Savory^° show that the amino-acid grouping is that of a 

 typical protein, with a liigh proportion of aromatic radicals, similar 

 proteins not being found in the tumors or muscles of a typical case. 

 In fact, the amino-acid content, as given below, indicates that Bence- 

 Jones protein is as distinct from other proteins in chemical composition 

 as in its physico-chemical properties. The amino-acids, in round 

 numbers, were isolated in the following percentage proportions of the 

 entire protein: Valine-leucine fraction, 14; glutamic acid, 8; aspartic 

 acid, 2; proline, 2.7; phenylalanine, 4.8; t3T0sine, 4.2; tryptophane, 

 0.8; cystine, 0.6; arginine, 6; histidine, 0.8; lysine, 3.7; sulphur, 1.2. 

 An important point in this work is the agreement in composition of 

 the proteins from two different cases, being identical within the hmits 

 of the analytic methods, showing that the protein is of constant and 

 characteristic properties. 



Occurrence of "Myelopathic Albumosuria." — Not all eases of 

 multiple myeloma show the presence of Bence-Jones protein in the 

 urine, however, and it is present occasionally in other conditions. 

 Multiple bone involvement by other tumors does not often cause 

 "albumosuria."" There is no evidence that it occurs in the normal 

 body, even in the bone-marrow, or that it is produced as a step in the 

 splitting of any form of proteins. A few cases of supposed osteomala- 

 cia have been reported, with the Bence-Jones bodj^in the urine, but on 

 more careful investigation these seem to have been unrecognized mye- 



'9 Zeit. physiol. Chem., 1900 (30), 200. 



'« Jour, of Physiol., 1911 (42), 189. 



'' A case of this kind has, however, been described by Oerum (Ugeskrift f. 

 Lager., 1904, No. 24), in which the bone tumors were multiple metastases of a 

 gastric carcinoma. See also Boggs and Guthrie, Amer. Jour. Med. Sci., 1912 

 (144), 803. 



