Chapter 30 

 Photochemistry of Nucleic Acids and Their Constituents 



D. Shugar 



Institute of Biockemistry and Biophysics, Academy of Sciences; and State 

 Institute of Hygiene, Warsaw, Poland 



I. Introduction 40 



II. Principles of Photochemistry 40 



1 . General ' 40 



2. The Primary Photochemical Process 42 



3. Excited States of Molecules 42 



4. Free Radicals in Biological Systems 44 



5. Secondary Photochemical Processes 46 



III. Photochemical Techniques 46 



1 . Sources 46 



2. Preparative Photochemistry 48 



3. Light Intensity Measurements 48 



4. Conversion Factors for Light Intensity 49 



IV. Optical Properties and Techniques 50 



1 . Far Ultraviolet Spectra 50 



2. Aqueous Solution Infrared Spectroscopy 51 



3. Dihydropyrimidine Derivatives 52 



4. Hyperchromicity in Oligo- and Polynucleotides 54 



5. Xucleoproteins and Viruses 59 



V. Photochemistry of Nucleic Acid Constituents 61 



1 . Carbohydrates 62 



2. Purine Derivatives 63 



3. Purine Nucleotides and Nucleotide Coenzymes 66 



4. Pyrimidines and Pyrimidine Nucleosides and Nucleotides 68 



VI. Photochemistry of Nucleic Acids 79 



1 . Physicochemical Studies 79 



2. Biological Inactivation 81 



VII. Reversibility of Nucleic Acid Photolysis 86 



1 . Physicochemical Studies 86 



2. Biological Studies 88 



VIII. Radiation Receptors in Living Organisms 90 



IX. Viruses 93 



X. Photoreactivation 96 



XL Addendum 100 



XII. General Bibliography 103 



39 



