A MICRO-UREASE METHOD FOR THE DETERMINA- 

 TION OF UREA 



ANTON R. ROSE and KATHERINE R. COLEMAN 

 (Research Laboratory, Fenton B. Turck, M.D., Director, New York City) 



The discovery by Takeuchi/ that from the soja bean {Glycine 

 hispida) an enzyme can be extracted whose specific action is the con- 

 version of urea into ammonium carbonate, offered the biological 

 chemist a new means of determining this characteristic urinary 

 constituent, which was not long delayed in application. The ear- 

 hest attempts at the estimation of urea by this agent are those of 

 Marshall. ^ More recently the properties of the enzyme have been 

 studied by Van Slyke and Cullen,^ who have given us a procedure 

 by which it can be concentrated as a convenient soluble powder, and 

 have also described a method of determining urea quantitatively by 

 means of urease. 



The possibility of adapting these methods to the work of this 

 laboratory on the chemistry of bacteria, where only minute quanti- 

 ties or very small samples might be expected, led to a series of experi- 

 ments that may be described here with profit. 



The original plan gave very encouraging results and may be 

 briefly stated as follows : The soja bean was finely ground, passed 

 through a 20-mesh sieve, and placed in a stoppered bottle. When 

 a determination or a series of determinations was to be made, i gm. 

 of this flour was kept in 10 c.c. of water for an hour, with occa-t 

 sional shaking, and then either filtered or centrifuged. An amount 

 of the Solution in which the urea was to be determined was carefully 

 pipetted into a Jena test tube. To this was added 2 c.c. of the 



1 Takeuchi : Jour. Coli. Agric, Univ. Tokio, 1909, i, p. i. For earlier refcr- 

 ence see Marshall's first paper cited below. 



2 Marshall : Jour. Biol. Chem., 1913, xiv, p. 283 ; xv, p. 495. 



3 Van Slyke and Cullen : Proc. Soc. Exp. Biol. Med., 1913, ix, p. 57. See 

 also Armstrong and Horten : Proc. Roy. Soc. Land., 1913, Ixxxvi, p. 328 ; Kiesel : 

 Zeit, physiol. Chem., 191 1, Ixxv, p. 169. 



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