MOLECULAR CONFIGURATION OF NUCLEIC ACIDS 



29 



(i • I A) (Fig. 12). We intend to use these data in future Fourier analysis. 

 Another means of confirming the correctness of our analysis is to substitute 

 bromide for chloride in the structure and show that the height of the sup- 

 posed halide peak increases in the expected manner. We are at present 

 obtaining intensity data from bromide-containing DXA. 



30^ /ft/cr Zinc 



Fig. 12. X-ray diffraction photograph (with Mr. X. E. Chard) of lithium salt 

 of DXA showing i ■ i A reflection on the 30th layer line. 



Notes on the molecular configuration of RNA 



Improved methods of preparing RXA and the separation of various 

 types of RXA have helped to clarify X-ray diffraction studies of RXA. 

 Soluble RXA (transfer RXA with amino acids attached) can be oriented 

 in sheets and gives diffraction patterns which, though rather diffuse, are 

 clearly similar to those of DXA [20]. It is fairly certain that these RXA 



