ULTRAVIOLET ABSORPTION SPECTRA 



187 



bonds will show appreciable absorption in the region 2200 3000 A 

 (Dannenberg, 1939; Fieser and Fieser, 1949). Thus steroids that contain 

 only isolated ketone groups (androsterone) have only a very weak absorp- 



1.2 



1.0 



8- 



o 



0.6 





-^ 



02 



220 



230 



240 



290 



300 



310 



250 260 270 280 



WAVE LENGTH, mjl 



Fig. 5-16. Change in ultraviolet absorption spectrum of thymu.s deoxyribonucleic acid 

 upon digestion with deoxyribonuclease. I, digested; II, undigested. {Kunitz, 1950, 

 reproduced from the Journal of General Physiology.) 



16.000 



14.000 



12.000 



10.000 



o 

 o 



2 



8000 - 



< 6000 



-J 



o 



s 



4000 - 



2000 



210 



220 



230 



240 



290 



300 



310 



320 



250 260 270 280 



WAVE LENGTH, mji 



Fig. 5-17. Absorption spectra of five deoxyribonucleotides at pH 4.30. I, deoxy- 

 guanj'lic acid; II, deoxyadenylic acid; III, deoxycytidylic acid; IV, deoxy-5-methyl 

 cytidylic acid; V, thymidylic acid. {Sinsheimer, 1954.) 



tion at about 2900 A (e = 43). Steroids with a and /3 unsaturated 

 ketones will have a strong absorption in the region 2300-2000 A (for pro- 

 gesterone, Xmax. = 2370 A, and e = 17,000) and a much weaker band near 

 3200 A (e ~ 10-20) (Morton, 1942). 



