Investigation of molecular mechanisms in photodynamic action and radiobiology with nanosecond flash photolysis and pulse radiolysis. Progress report, July 1, 1975--June 30, 1976

Technical Report · Mon Mar 01 04:00:00 EST 1976

DOI:https://doi.org/10.2172/7352777· OSTI ID:7352777

Grossweiner, L I

Flash photolysis studies have shown that exposed tyrosyl or tryptophyl residues of enzymes are photoionized at approximately the same quantum efficiency as the aqueous amino acids. Comparisons with permanent damage indicate that this primary process contributes to inactivation when a photolyzed aromatic residue is essential or is located adjacent to a catalytic, non-chromoporic residue. Studies on sensitization by the phototherapeutic drug, 8-methoxypsoralen (8-MOP), show the triplet state can lead to singlet oxygen generation and that weak binding to poly (dA-dT) suppresses this process. 8-MOP was found to be potent sensitizer of yeast photoinactivation with negligible post-irradiation recovery. Spinlable ESR measurements made on yeast cells after photodynamic treatment show that the membrane damage generated by the penetrating dye Toluidine Blue 0 is more extensive than the external dye, Eosin Y. In related ionizing radiation studies, it was found that 8-MOP is an anoxic radiosensitizer of T7 phage, attributed to enhancement of crosslinks; that complexing of eosin to lysozyme sensitizes the enzyme to oxidizing radicals; that the reactions of Br/sub 2//sup -/ and (CNS)/sub 2//sup -/ with tryptophan generate the same initial radical as uv-excited photoionization.

• Research Organization: Illinois Inst. of Tech., Chicago (USA)
• OSTI ID: 7352777
• Report Number(s): COO-2217-15
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
560110 -- Radiation Effects on Biochemicals-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKOXY RADICALS
AMINO ACIDS
ANTICOAGULANTS
AROMATICS
AZO COMPOUNDS
AZO DYES
BACTERIOPHAGES
BIOLOGICAL EFFECTS
BIOLOGY
BIOMASS
CARBOXYLIC ACIDS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DRUGS
DYES
ELECTRON SPIN RESONANCE
ENERGY SOURCES
ENZYMES
EOSIN
FUNGI
HETEROCYCLIC COMPOUNDS
HYDROXY ACIDS
INACTIVATION
INDICATORS
MAGNETIC RESONANCE
METHOXY RADICALS
MICROORGANISMS
MOLECULAR BIOLOGY
ORGANIC ACIDS
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PARASITES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PLANTS
PSORALEN
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOBIOLOGY
RADIOLYSIS
RADIOSENSITIZERS
RENEWABLE ENERGY SOURCES
RESIDUES
RESONANCE
RESPONSE MODIFYING FACTORS
TOLUIDINE BLUE
VIRUSES
YEASTS