RIBOSEXUCLEIC ACID IN THE JENSEN SARCOMA OF THE KAT 681 



an aliquot of the solutions obtained was used for the colorimetric deter- 

 minations and another aliquot for the determinations of the radio- 

 activity. 40 mgm Na2HP04 were added to the aliquot, which was used 

 for the determinations of the radioacti\'ity, and then the phosphorus 

 was precipitated as magnesium-ammonium phosphate. 



As already observed by Schmidt and Thanhauser and as shown 

 below, the ribonucleic fractions always contain some inorganic P which 

 possibly originates from some protein phosphorus present in the tissue 

 and decomposed in the alcaline solution. The presence of inorganic P 

 might also be explained by assuming that despite thorough extraction 

 either some inorganic P or organic P compound was left in the tissue, 

 which are identified as inorganic P in the alcaline solution of the tissue. 

 It is also possible that a minute amount of nucleic acid P is split off in 

 the alcaline solution. 



The inorganic P present in an aliquot of the solution of ribosenucleotides 

 was determined by the method of Delory^^). Owing to the fact that large 

 amounts of proteins are present in the solution containing the ribosenucle- 

 otids it was not possible to use the conventional methods for determining P. 

 When calculating the specific activity of the ribosenucleic acid P from the 

 inorganic P content and the activity of the ashed aliquot of the final 

 solution, it must be taken into account that the whole amount of in- 

 organic P present does not originate through ashing of the ribosenucleic 

 acid P, because part of it is a remnant of the inorganic P, which has been 

 present before ashing (see above). We have to deduct the values corre- 

 sponding to the contaminating P both from the activity measured and 

 from the inorganic P colorimetrically determined in the ashed ribose- 

 nucleic P fraction. 



Since the total activity of the last mentioned component is mostly 

 much lower than the activity of the- ribose P fraction, the corrected 

 values do not differ much from the non-corrected ones. 



The following example illustrates the method used in determining the specific 

 activity of nucleic acid P. Three sarcomata of an aggregate weight of 17.6 g weie 

 pooled. The minced tissue was extracted with ice-cooled 7 per cent trichloracetic 

 acid. The solution was filtered off through a Biichner fuel covered by a thick 

 layer of hyflo. The tissue was repeatedly washed with 1 per cent CCI3COOH. 

 The last wash water did not show any colouring of amidol. The total value of 

 1 per cent CCI3COOH added amounted to 800 ml. Trichloracetic acid present in 

 Ihe tissue was quantitatively removed by washing with water. The tissue was 

 then refluxed with 40 volumes of absolute alcohol for 14 hours. The ether — drycd 

 tissue was again extracted with 20 volumes of 7 per cent CCI3COOH and the pro- 

 cedure described above repeated. After having been dried in vacuum, the tissue 

 was refluxed with 3 : 1 alcohol-ether mixtuie for 11 hours. After removing the 

 alcohol by washing with ether and drying in vacuum, the tissue was a third time 



(i^Delgry, Biochem. J. 32, llGl (1938). 



