MOLECULAR C O N \ I G U H A I I O N OF NUCLEIC ACIDS 



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m 1 " *r 



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Fig. 9. X-ray diffraction pattern of microcrystalline fibres of DNA in the A con- 

 figuration. (Photograph with H. R. Wilson; DNA by L. D. Hamilton.) 



RNA resembled DNA (Rich 22 ). The diffraction patterns of RNA (Rich and 

 Watson 23 ) bore a general resemblance to those of DNA, but the nature of 

 pattern could not be clearly distinguished because of disorientation and 

 diffuseness. An important difficulty was that there appeared to be strong 

 meridional reflections at 3.3 A and 4 A. It was not possible to interpret these 

 in terms of one helical structure. 



s-50 



