904 



METABOLISM OF THE CANCER CELL 



12 



this area may reveal the more specific function of the deoxy components in the 

 biosynthesis and mobiUzation of DNA required for celhdar divisions. 



Studies on the isolation and determination of the free nucleotides have been 

 carried out by Schmitz (1954, 1954a). Values were obtained for the 5'-mono-, di- 

 and triphosphates of adenosine, guanosine, cytidine and uridine from per- 

 chloric acid extracts of mouse ascite tumors (Fig. 4). 



The ratio of diphosphopyridine nucleotides to AMP in ascites tumor was 1:1, 

 while in solid tumors the 

 values ranged from 1 13 to 

 1 :5, AMP being present in 

 the highest concentration. 

 The composition of the 

 RNA of the ascites cells was 

 cjuite similar to that of oth- 

 er tumors (Schmitz et al., 

 1955). DeLamirande et al. 

 (1955) reported the follow- 

 ing variation in hepatic 

 guanylic acid from normal 

 liver: nuclear fraction + 



420 



12.2%, mitochondrial frac- 

 tion +22; microsomal frac- 

 tion — 1.9, supernatant frac- 

 tion +51.7%. 



Fig. 4. The ordinate is the UV absorption at 260 [jl [d =■■ 

 10 mm) of the fractions plotted on the abscissa. The frac- 

 tions were separated by means of an automatic fraction- 

 collector. Each fraction had a volume of 4 ml. The frac- 

 tions were eluted with gradually increasing concentrations 

 oiO-^ ^N HCOOH (1-140) and of 4;\^HCOOH — 4JV 

 HCOOH + i.A^HCOONH4 (141-end). The following 

 abbreviations have been used: MP, monophosphate; DP, 

 diphosphate; TP, triphosphate; A, adenosine; G, gua- 

 nosine; C, cytidine; U, uridine; I, inosine; DPN, diphos- 

 phopyridinenucleotide. The extinction values beyond the 

 scale are: DPN: 1.9, 4.05, 2.68; AMP: 4.16, 5.77, 2.19; 

 ADP: 2.06, 2.70, 3.07, 2.83, 2.07; ATP: 1.89, 2.22, 2.60, 

 2.70, 2.80, 2.60, 2.40, 1.935 (Schmitz, 1954, from his 

 original paper). 



{in) Nucleic acids and nucleo- 

 proteins, A comprehensive 

 analytical study has been 

 completed by Caspersson 

 and associates (Caspersson, 

 1 950) as to the role of nucleic 

 acids and nucleoproteins in 



the process of cellular reduplication. Their findings would indicate that the 

 appearance of nucleolar substances and the formation of cytoplasmic proteins are 

 closely related (see Chapter 3). The nucleoli and the cytoplasmic nucleotides are 

 conspicuous in the pancreas where the cell has the capacity to produce its own 

 weight in protein during a 24 h. period. Caspersson believes that the chromatin 

 associated with the nucleolus or the heterochromatin is involved in the production 

 of proteins in the cell. Deoxyribonucleotides, according to Caspersson, participate 

 in the reproduction of the gene proteins in the chromosomes while the ribonucleo- 

 tides are involved in the formation of proteins of the cytoplasm. These investigators 

 carried out microspectrographic studies on a large number of human tumors. The 

 tumor cell, they believe, has the same systems for protein formation in the nucleus 

 and the cytoplasm as are present in normal cells. In the cancerous cell the endo- 

 cellular inhibitory mechanism which controls protein formation is lost or altered 

 in some way. 



