Original Title: Photochemistry Of Proteins And Nucleic AcidsPhotochemistry of Proteins and Nucleic Acids deals with photobiology. The book briefly introduces the principles of photochemistry, with a short discussion on absorption spectra and related absorbing structures, as well as on the general nature of photochemical reactions in solutions. The following information covers how proteins, nucleic acids, viruses, and their basic structures are chemically and physically affected when exposed to visible radiation and ultraviolet light. The book explains that the site of action of the ultraviolet light when applied to proteins in a small active center shows that other parts of the protein are also affected, considered as an energy transfer. Then the general conclusions pertaining to the physicochemical and chemical changes in nucleic acids through directed radiation doses that are big enough to induce modifications are enumerated. The text further explains that the physicochemical modifications, which occur when proteins are irradiated, can accompany loss in enzyme activity. The kinetics of inactivation of dry enzymes is compared to the photochemistry of enzymes in a solution. The inactivation of viruses is important as the process of replication can cause some formed viruses to spread in its environment, worsening the state of infection. Hence, the problem which components in a biological system absorb effective radiation is analyzed. The book is suitable for microbiologists, microchemists, and laboratory researchers and scientists dealing with infectious diseases.