CHEMICAL SPECIFICITY OF NUCLEIC ACIDS 



I 23 4 5 6 7 8 9 10 II 12 13 



Fig. 1. Schematic representation of the position on the paper chromato- 

 gram of the purines and pyrimidines following the separation of a mixture. 

 A = adenine, G = guanine, H = hypoxanthine, X = xanthine, U = uracil, 

 C = cytosine, T = thymine. The conditions under which the separations 

 were performed are indicated at the bottom: a = acidic, n = neutral, B = 

 n-butanol, M = morphohne, D = diethylene glycol, Co = collidine, Q = 

 quinohne. (Taken from E. Vischer and E. Chargaff24.) 



morpholine, diethylene glycol, water (column 5 in Fig. 1); and 

 (2) ^z-butanol, diethylene glycol, water in an NH3 atmosphere 

 (column 11). The second system Usted proved particularly con- 

 venient. The separation of the pyrimidines is carried out in 

 aqueous butanol (column 1). 



Following the separation, the location of the various adsorption 

 zones on the paper must be demonstrated. Our first attempts 

 to bring this about in ultraviolet light were unsuccessful, probably 

 because of inadequate filtration of the light emitted by the lamp 

 then at our disposal. For this reason, the expedient was used of 

 fixing the separated purines or pyrimidines on the paper as 



