Photochemistry of Proteins

The amide functionality plays an important role in the physical and chemical properties of proteins and peptides, especially in their ability to be involved in the photoinduced electron transfer process. Polyamides and proteins are known to take part in the biological electron transport mechanism for oxidation-reduction and photosynthesis processes. Therefore studies of the photochemistry of proteins or peptides are very important. Irradiation (at 254 nm) of the simplest dipeptide, glycylglycine, in aqueous solution affords carbon dioxide, ammonia and acetamide in relatively high yields and quantum yield (0.44)202 (equation 147). The reaction mechanism is thought to involve an electron transfer process. The isolation of intermediates such as IV-hydroxymethylacetamide and 7V-glycylglycyl-methyl acetamide confirmed the electron-transfer initiated free radical processes203 (equation 148). 

A. D. McLaren and D. Shugar, Photochemistry of Proteins and Nucleic Acids, Pergamon, Oxford, 1964... 

McLaren, A. D., and D. Shugar Photochemistry of Proteins and nucleic acids, S. 184. Oxford Pergamon Press 1964. 

Kaplan EH, Campbell ED, McLaren AD. Photochemistry of proteins. VIII. Inactivation of insulin by ultraviolet light. Biochem Biophys 1950 4 493-500. 

Helene, C. Excited state interactions and energy transfer processes in the photochemistry of protein-nucleic add complexes. In Excited States of Biological Molecules. Birks, J. B. (Ed.) p. 151, London - New York - Toronto - Sydney Wiley 1976... 

Photochemistry of proteins is derived from diose of its amino acid residues. In addition, important photochemical processes in proteins involve the splitting of the disulfide bridges. Furthermore, DNA-protein cross-linking involves the addition of thymine in DNA with cystine in protein. This addition process has been discussed above. In the case of DNA, UV irradiation can also lead to the breaking of either one or both DNA strand and infra- and inter-molecular DNA cross-linking. The photochemistry of RNA is very similar to that of DNA. 

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