Energy transfer mechanisms in photobiological reactions. Progress report, 1 August 1975--30 April 1976
As in our earlier work on the sensitized photooxidation of substituted phenylalanines, ring substituents were found to have a marked effect on the photooxidation of uracil. This compound was selected as a typical pyrimidine for detailed studies of the mechanism of photooxidation of molecules of biological importance. The photooxidation of a series of 5-substituted uracils as sensitized by eosin Y, ruthenium bipyridyl, 3-methyl-lumiflavin and methylene blue was studied using oxygen electrode and flash photolysis techniques. Different substituents had very different effects on the rates of photooxidation with a given dye, and some substituents could shift the mechanism from a singlet oxygen pathway to an electron abstraction pathway (or vice versa). A study of the effects of porphyrin structure in relation to photosensitizing characteristics was completed. An examination of the localized selective photooxidation of amino acids in the vicinity of the heme binding site of horseradish peroxidase was made using specifically-bound protoporphyrin IX and other porphyrins as sensitizers. Preliminary studies were carried out on the use of sensitized photooxidation as a tool to study the contribution of histidine-containing crosslinks to the mechanical-thermal properties of mammalian tendon as well as the role of membrane properties in determining the rate and direction of swimming of certain microorganisms.
- Research Organization:
- Utah Univ., Salt Lake City (USA). Dept. of Biology
- OSTI ID:
- 7279484
- Report Number(s):
- COO-875-176
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINES
AMINO ACIDS
AZINES
AZOLES
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
DECOMPOSITION
DRUGS
ENERGY TRANSFER
ENZYMES
HALIDES
HALOGEN COMPOUNDS
HEME
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
HYDROXY COMPOUNDS
IMIDAZOLES
KINETICS
METHYLENE BLUE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
OXIDOREDUCTASES
PEROXIDASES
PHENOTHIAZINES
PHENYLALANINE
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
PHOTOSENSITIVITY
PIGMENTS
PORPHYRINS
PYRIMIDINES
REACTION KINETICS
SENSITIVITY
URACILS