PHYSIOLOGICAL AND BIOCHEMICAL TECHNICS 193 



original a-amino acid, is known as transamination. The technics 

 employed to study the transaminases are varied, but all measure the 

 appearance or disappearance of the keto or amino acid. Green et al. 

 (1945) discussed keto acid measurements, Cohen (1940) aspartate meas- 

 urement by the chloramine-T reaction, Lichstein et al. (1945) amino acid 

 measurement by decarboxylase method, and Feldman and Gunsalus 

 (1950) amino acid measurement by paper-partition chromatography. 

 The symposium on amino acid metabolism edited by McElroy and Glass 

 (1954) is recommended as a source of reference to specific analytical 

 procedures. 



Nucleic acids, purines, and pyrimidines. Studies of nucleic acid 

 metabolism necessitate the measurement of these complex substances 

 themselves as well as the constituent purines, pyrimidines, carbohydrates, 

 and phosphorus. A preliminary step involves the removal of nucleic 

 acids from the rest of the cell material, followed by separation of the two 

 types of nucleic acids, desoxypentose and pentose, and their quantitative 

 analysis. The nucleic acids are then hydrolyzed, and the quantities of 

 the constituent parts measured. 



The treatise of Chargaff and Davidson (1955) contains a complete con- 

 sideration of methods and results of nucleic acid research. Several useful 

 general reference sources also are cited: Cold Spring Harbor Symposia 

 (1947); Symposia of the Society for Experimental Biology (1947); 

 Symposia on Biochemistry of Nucleic Acids (1951); as well as ion- 

 exchange methods (Cohn, 1951) and paper chromatography methods 

 (Hotchkiss, 1948; Carter, 1950) for purines and pyrimidines. 



Phosphorus Metabolism 



Although many phosphorylated compounds of biochemical importance 

 have been described, isolated, and characterized, most of the work has 

 dealt with animal tissues, yeast being the only microorganism that has 

 received any appreciable attention in the past. However, it is probable 

 that similar studies with microorganisms will yield analogous results, and 

 indeed, work with the latter is accumulating. Thus, it appears valid to 

 include here a brief description of phosphorylated compounds, regardless 

 of their origin. 



The manual of Umbreit et al. (1949) presents methods for the analysis 

 of phosphorylated intermediates as well as technics for their isolation and 

 synthesis. The isolation and purification of phosphorylated compounds 

 derived from cellular material are usually accomplished by fractional pre- 

 cipitation of their metallic salts, but more recently, technics have been 

 described employing the principle of solvent distribution (Plant et al., 



