ACTION OF ULTRAVIOLET LIGHT ON VIRUSES 167 



Strong sharpening is not apparent at low temperatures. 



Since no appreciable low-temperature sharpening of the action 

 spectrum occurs, it is likely that the type of absorption taking 

 place involves transition to closely spaced levels — i.e., is near 

 dissociation. Since many photons are absorbed to produce a 

 one-hit (in some cases) inactivation, many excited bonds must 

 lose energy and return to the original configuration. Since side- 

 chain absorption is important, there is probably a severance of 

 side-chain cross linkage which forms a part of the process of 

 inactivation. 



We wish to repeat that the study of virus action spectra is 

 in its very early stages. As the varied kinds of virus inactivation 

 are treated separately, the information can be used to give an 

 inferred structure in terms of electromagnetic radiation, which 

 can be used for comparison with inferences from ionizing 

 radiation and thermal measurements. 



References 



For general references: McLaren, A. D., Advances in Enzymol. 9, 75 (1949), 

 and Beavan, G. H., and Holiday, E. R., Advances in Protein Chem. 7, 360 

 (1952). More detailed references follow below. 



Apker, L., and Taft, E., Phys. Rev. 82, 814 (1951). 



Beaven, G. H., and Holiday, E. R., Faraday Society Symposium, 9, 494 

 (1950). 



Brown, G. L., and Randall, J. T., Nature 163, 209 (1949). 



Butenandt, A., Friedrich-Freksa, H., Hartwig, S., and Scheibe, G., Hoppe- 

 Seyler's Z. Physiol. Chem. 274, 276 (1942). 



Dulbecco, R., Nature 163, 949 (1949). 



Dulbecco, R., /. Bacteriol. 59, 329 (1950). 



Fluke, D. J., Phys. Rev. 82, 302 (1951). 



Fluke, D. J., In course of publication (1953). 



Fluke, D. J., and Setlow, R. B., Phys. Rev. 78, 335 (1950). 



Gates, F. L., J. Gen. Physiol. 14, 31 (1930). 



Gates, F. L., J. Exptl. Med. 60, 179 (1934). 



Goldfarb, A. R., Saidel, L. J., and Mosovich, E., J. Biol. Chem. 193, 397 

 (1951). 



Hamm, J. S., and Piatt, J. R., J. Chem. Phys. 20, 335 (1952). 



Heller, W., and Marcus, A., Phys. Rev. 84, 809 (1951). 



Holiday, E. R., Biochem. J. 30, (2) 1795 (1936). 



Hollaender, A., and Oliphant, J. W., J. Bacteriol. 48, 447 (1944). 



Hollaender, A., and Duggar, B. M., Proc. Natl. Acad. Sci. U.S. 22, 19 

 (1936). 



Jones, H. N., Chem. Revs. 41, 357 (1947). 



