Anion radicals of pheophytin and chlorophyll A: their role in the primary charge separations of plant photosynthesis

Journal Article · Wed Sep 13 00:00:00 EDT 1978 · J. Am. Chem. Soc.; (United States)

OSTI ID:6573102

Jujita, I; Davis, M S; Fajer, J

Redox, optical, and paramagnetic characteristics of the anion radicals of chlorophyll(Chl./sup -/) and pheophytin(pheo./sup -/) were measured. Solutions of Chl./sup -/ and Pheo./sup -/ in dimethylformamide(DMF) were prepared by controlled electrolysis of oxygen free solutions in which the solvent had been pretreated with activated molecular sieves followed by activated neutral alumina. The electrolysis reactions were reversible as one-electron oxidation of the radicals regenerated better than 90% of the original chlorins. ESR and ENDOR spectra showed no differences in samples prepared in deuterated DMF (99.5% d/sub 7/), even after prolonged standing--indicating that no significant reactions occurred with solvent protons at sites of high spin densities. A comparison of the optical changes induced by light in a Chl protein complex of photosystem II poised at -0.49 V (vs, NHE) as reported in the literature and the difference spectra obtained on reduction of Pheo and Chl in DMF is drawn. The authors conclude that the first reduced chemical products of green plant photosynthesis are the anions of pheophytin in the photosystem which oxidizes water (photosystem II), and the anions of chlorophyll in the photosystem which reduces carbon dioxide (photosystem I). 4 figures, 1 table, 39 references.

• Research Organization: Brookhaven National Lab., Upton, NY
• OSTI ID: 6573102
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 100:19; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTRA
AMIDES
ANIONS
CARBOHYDRATES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHLOROPHYLL
ELECTROLYSIS
ELECTRON SPIN RESONANCE
ENDOR
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
IONS
KINETICS
LYSIS
MAGNETIC RESONANCE
MAGNETISM
OPTICAL PROPERTIES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SOLVENTS
OXIDES
OXYGEN COMPOUNDS
PARAMAGNETISM
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYSICAL PROPERTIES
PHYTOCHROMES
PIGMENTS
PORPHYRINS
RADICALS
REACTION KINETICS
REDOX REACTIONS
RESONANCE
SAMPLE PREPARATION
SOLVENTS
SPECTRA
SYNTHESIS
WATER
YIELDS