i'(nru.\'i/o\ ()!■' I h'lc .\<ii) 621 



tion of sodiiuii urate. How the uric acid is kept in solutiiui in tile 

 blood is not exactly understood, but Gudzent believes that uric acid 

 can exist in the blood only as the monosodiuni urate, and in the less 

 soluble but more stable lactim form, which is soluble only to the extent 

 of 8.3 mp;. per 100 ec. serum (the lactam foi-m beinj^ soluble up to 18 

 mg.). However, amounts over 20 m<z:. i)er 100 c.c. have been detected 

 in the blood of nephritics; here solution may have been aided by the 

 other retained metabolites. Bechhold "^ and others have maintained 

 that urates may be present in the blood in a colloidal state which -can- 

 not pass out throu^li the kidneys. 



FORMATION OF URIC ACID " 



The origin of uric acid is chiefly, although not exclusively, from 

 the nucleoproteins, and it is customarA' to refer to uric acid formed 

 from, the nucleoproteins of the foods as "exogenous'^ uric acid, in con- 

 trast to the " endogenous" wr'xQ, acid that is formed from the nucleo- 

 proteins of the body cells during their catabolism. This may be read- 

 ily explained hy a brief consideration of the composition of the nucleo- 

 proteins. The nucleoproteins may be looked upon as salts formed 

 through combination of proteins with nucleic acid. Nucleic acid in 

 turn is a compound of phosphoric acid with purine bases, pyrimidine 

 bases, and carbohydrate radicals, constituting a complex sort of glu- 

 coside. 



A long series of careful analytical studies has at last shown us that 

 nucleic acids, are, whatever the source, quite similar in composition, 

 consisting always of a complex containing phosphoric acid, the two 

 amino purines (adenine and guanine), two pyrimidines (either cyto- 

 sine and uracil or cytosine and thymine) ; and a carbohydrate, which 

 may be either a pentose or a hexose. Apparently there are two sorts 

 of nucleic acids, one from plants, which contains always uracil and 

 pentose, and one from animal tissues, containing instead thymine and 

 a hexose. So constant are the findings in regard to these compounds 

 that it has seemed feasible to consider their manner of union in the 

 intact nucleic acid molecule, and Levene and Jacobs have ]n-oposed as 

 the structure of thymus nucleic acid the following arrangement : 



H POs — CeH.oOi — CsHsNeO 



! (guanine sroup) 



? 



U=P04 — CeHsOa — CsHbN^O: 



1 (thymine group) 



? 



H2PO4 — CeFs02 — C4H4N3O 



I (cvtosine group) 



o 



H PO3 — CeH-oO* — C5H4N5 



(adenine group) 



saBiocliem. Zeit., 1914 (64), 471. 



"See review in International Clinics, 1910, XX (J, 76. 



