444 PHYSIOLOGICAL CHEMISTRY 



filter this solution, and after testing again for nucleoprotein with very dilute acetic- 

 acid, try the biuret test. If this test is positive the presence of proteose is indicated. 1 



Urobilin does not ordinarily interfere with this test since it is almost entirely 

 dissolved by the absolute alcohol when the proteose is precipitated. 



4. Detection of "Bence-Jones* Protein." Heat the suspected urine very 

 gently, carefully noting the temperature. At as low a temperature as 4oC. a 

 turbidity may be observed, and as the temperature is raised to about 6oC. a 

 flocculent precipitate forms and clings to the sides of the test-tube. If the urine 

 is now acidified very slightly with acetic acid and the temperature further raised 

 to iooC. the precipitate at least partly disappears; it will return upon cooling 

 the tube. 



This property of precipitating at so low a temperature and of dissolving at a 

 higher temperature is typical of "Bence- Jones' protein" and may be used to differ- 

 entiate it from all other forms of protein material occurring in the urine. 



NUCLEOPROTEIN 



There has been considerable controversy as to the proper classifica- 

 tion for the protein body which forms the "nubecula" of normal urine. 

 By different investigators it has been called mucin, mucoid, phospho- 

 protein, nucleoalbumin, and nucleoprotein. Of course, according to 

 the modern acceptation of the meanings of these terms they cannot be 

 synonymous. Mucin and mucoid are glycoproteins and hence contain 

 no phosphorus (see page in), whereas phosphoproteins and nucleo- 

 proteins are phosphorized bodies. It may possibly be that both these 

 forms of protein, i.e., the glycopr-otein and the phosphorized type, 

 occur in the urine under certain conditions (see page 413). In this 

 connection we will use the term nucleoprotein. The pathological con- 

 ditions under which the content of nucleoprotein is increased includes 

 all affections of the urinary passages and in particular pyelitis, nephritis, 

 and inflammation of the bladder. 



EXPERIMENTS 



1. Detection of Nucleoprotein. Place 10 c.c. of urine in a small beaker, 

 dilute it with three volumes of water to prevent precipitation of urates, and make 

 the reaction very strongly acid with acetic acid. If the urine becomes turbid 

 it is an indication that nucleoprotein is present. 



If the urine under examination contains albumin the greater portion of this 

 substance should be removed by boiling the urine before testing it for the pres- 

 ence of nucleoprotein. 



2. Tannic Acid Precipitation Test (Ott). Mix 25 c.c. of the urine with 

 an equal volume of a saturated solution of sodium chloride and slowly add 



1 If it is considered desirable to test for peptone the proteose may be removed by satu- 

 ration with (NH4) 2 SO4 according to the directions given on p. 119 and the filtrate tested 

 for peptone by the biuret test. 



