Photochemistry of enzymes and viruses. Progress report, 1 January 1968-31 December 1968

Technical Report · Mon Jan 01 04:00:00 EST 1968

OSTI ID:6565067

McLaren, A D; Evans, N; Hidalgo-Salvatierra, O

A history of the photochemistry of tobacco mosaic virus is presented. The photochemistry of free infectious nucleic acid differs from that exhibited by nucleic acid irradiated in intact virus. The quantum yield, under nonphotoreactivating conditions, for inactivation of tobacco mosaic virus RNA (TMV-RNA) by ultraviolet radiation (254 mu) is essentially independent of the RNA concentration but varies appreciably with the ionic strength of the irradiation solvent. Photoreactivation of inactivated TMV-RNA is dependent on RNA concentration, ionic strength of solutions during irradiation, and on the light quality used for photoreactivation. Initially photoreactivation of irradiated nucleic acid on pinto bean increases linearly with time of illumination with white light. Maximum amounts of photoreactivation depend on the quality of light used. Photoreactivation does not occur at wavelengths above 550 nm. Photoprotection was not found. Inactivation of TMV-RNA by uv radiation is slower in D/sub 2/O than in H/sub 2/O, and TMV-RNA which has been inactivated in D/sub 2/O is photoreactivated faster. These deuterium isotope effects suggest that pyrimidine hydrates are photoreactivable lesions. The effect of HCN on the quantum yield for uv inactivation of TMV-RNA and on the percent photoreactivation was investigated. Some photoproducts produced by irradiation of poly U and poly C, in the presence of HCN were also studied. The ratio of the quantum yield for inactivation of TMV-RNA in the presence of HCN to that in the absence of HCN is 1.5, under non-photoreactivating conditions. The photohydration reaction in poly U is almost abolished by HCN, and the rate of dimerization is reduced to half by HCN. It is suggested that uracil dimers are somehow involved in photoreactivation of TMV-RNA inactivated at high ionic strength. (ERB)

• Research Organization: California Univ., Berkeley (USA). Dept. of Soils and Plant Nutrition
• DOE Contract Number: AT03-76EV72005
• OSTI ID: 6565067
• Report Number(s): UCB-34P116-5
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CHEMISTRY
CYANIDES
ELECTROMAGNETIC RADIATION
FREQUENCY DEPENDENCE
HEAVY WATER
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
INACTIVATION
INORGANIC ACIDS
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PARASITES
PHOTOCHEMISTRY
PHOTOREACTIVATION
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
RNA
TOBACCO MOSAIC VIRUS
ULTRAVIOLET RADIATION
VIRUSES
WATER