ACTION OF ULTRAVIOLET LIGHT ON VIRUSES 



153 



tions indicated in the lower curves of Fig. G.5b. The residt is 

 not a complete synthesis of the observed absorption spectrum 

 but is clearly rather close to it. 



Some unpublished work by Brown and Randall (privately 

 communicated by M. F. H. Wilkins) indicates that the ab- 

 sorption spectrum of TMV sharpens at low temperatures. The 



1.4 



1.2 



S 10 



08 



5 06- 



0.4 



2450 2500 



2600 



2700 

 Wavelength {K) 



2800 



2900 



Fig. 6.4. Absorption spectrum of insulin, taken by Suprynowicz. The con- 

 tinuous line is at room temperature, and the dotted line at 80° K. Six peaks can 

 be seen in a broad maximum at 2,750 A. There is some sharpening at low 

 temperatures. 



absorption spectrum of TMV at room and liquid-nitrogen 

 temperatures, as taken by Suprynowicz (1953), is shown in Fig. 

 6.6. The sharpening is quite apparent and can clearly be made 

 use of in analyzing the internal structure of this virus. The 

 wavelengths of the maxima observed are 2,578, 2,615, 2,644, 

 2,681, 2,811, and 2,905 A. Of these, 2,644 and 2,681 coincide 

 with two peaks found in insulin. TMV is predominantly protein 

 and so it is not surprising that the absorption extends so far to 

 the long- wave end. 



