Oxidized Cytochrome and Chlorophyll C2 + in Photosynthesis

Witt, H. T.; Mueller, A.; Rumberg, B.

doi:10.1038/192967a0

Cited by 124 publications

(44 citation statements)

References 6 publications

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“…The prominent feature of the low temperature as compared to the room temperature spectrum is the doubling of the amplitudes at 431 nm and 710 nm and a new positive band at 695 nm. Qualitatively similar negative bands have been found by different authors [1,2,4] and the positive band by Floyd et al [4].…”

Section: Photochemical Reactions In Sucrose Syrup At Low Temperaturesupporting

confidence: 88%

“…110°K) while dark reactions should be blocked if they are diffusion limited. In green plant photosynthesis reactions of the following pigments have been described as occurring at low temperature: Chl-a I (P-700) [1,2], Cyt b-559 [3][4][5][6][7], C-550 [5][6][7][8] and X-320 [9]. Cyt fwas believed to be photooxidized at low temperature [1,2] but new results show that this might not be the case [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…In green plant photosynthesis reactions of the following pigments have been described as occurring at low temperature: Chl-a I (P-700) [1,2], Cyt b-559 [3][4][5][6][7], C-550 [5][6][7][8] and X-320 [9]. Cyt fwas believed to be photooxidized at low temperature [1,2] but new results show that this might not be the case [4][5][6]. Furthermore a pigment with a band at 680 nm reacting at low temperature [4] has been assumed to be identical with the photoreactive chlorophyll-all (P-680) [10,111. Most experiments have been carried out with norreal suspensions of chloroplasts which increase straylight very much when frozen.…”

Section: Introductionmentioning

confidence: 99%

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Some photoreactions of spinach chloroplasts in sucrose syrup at high and low temperature

Witt

1973

FEBS Letters

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Section: Photochemical Reactions In Sucrose Syrup At Low Temperaturesupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Some photoreactions of spinach chloroplasts in sucrose syrup at high and low temperature

Witt

1973

FEBS Letters

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“…Various authors, e.g. DUYSENS et al 14, W~TT et al 15, LOSADA et al 16, ALLEN AND MURCHI01~, and GOEDHEER TM, considered the different functions of Ca67O and Ca68O. One of these forms is shown to induce cytochrome oxidation, whereas the other one causes cytochrome reduction upon excitation.…”

Section: Discussionmentioning

confidence: 99%

Studies on the red absorption band of chlorophyll a in vivo

Thomas

Hammans

Arnolds

1965

Biochimica et Biophysica Acta (BBA) - Biophysics including Phot

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SUMMARYIt was studied whether certain earlier observed weak shoulders on the red absorption band of chlorophyll a in vivo might represent anomalies due to overlap of absorption bands.The results are suggestive of the fact that no such anomalies occur. It is therefore concluded that the present study supports the concept holding that, at least, 6 rather than 4 chlorophyll a forms may be present in the state in vivo.The true position of the Ca68O absorption maximum is suggested to occur at a wavelength at least 4 m/~ longer than that actually measured in spectra of cells and chloroplast suspensions.The data suggest that Ca667 is likely to function in the Hill reaction with p-benzoquinone as an oxidant at least as efficiently as Ca67O.The possible significance of the chlorophyll a forms other than Ca67O, Ca68O, Ca695 and Ca7OO is discussed.

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“…This can be explained by the assumption that only simultaneous absorption by the "p" and "q" systems results in an effective use of absorbed light energy for photosynthesis. DUYSENS et al 29 attributed, in the red alga Porphyridium, oxidation of a cytochrome to a pigment system which is probably similar to our "q" system, while reduction of this cytochrome occurred as a result of irradiation with light of the same wavelengths as those exciting our "p" system (@ also HILL AND BENDALL 3° and WITT et al 31). In view of these results we suggest that our "quenching effect" is based on cytochrome oxidation, while the "promotion" is related to cytochrome reduction.…”

Section: Intact Photosynthesizing Cellsmentioning

confidence: 99%

Afterglow of chlorophyll in vivo and photosynthesis

1965

Solar Energy

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SUMMARYTwo pigment systems are involved in the afterglow of chlorophyll a-containing cells.Absorption in only one of these systems (promoting or "p" system) is effective in producing luminescence. If light is absorbed simultaneously by the other (quenching or "q" system), a decrease in luminescence results. Absorption in the "p" system is assumed to result in oxidation of water and reduction of a cytochrome. The afterglow is regarded as a chemiluminescence of chlorophyll excited by the recombination of photolysis products of water.Absorption in the "q" system is assumed to oxidise cytochrome and reduce a pyridine nucleotide. In this way electrons are removed from the "p" system and recombination prevented. Each system provides about half the energy needed in complete photosynthesis.Chloroplast luminescence is decreased by removal of electrons from the "p" system by addition of Hill reaction reagents.The "p" system includes mainly "short-wavelength chlorophyll a" and the accessory pigments, the "q" system mainly "long-wavelength chlorophyll a".Indications are presented that energy for both systems is provided by reversible photooxidation of chlorophyll a. The necessary separation between electrons leaving and electrons entering chlorophyll is assumed to result from a difference in molecular orbitals of ground and excited states, inferred from the differences between reversible photooxidation and photoreduction of chlorophyll in vitro.

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Oxidized Cytochrome and Chlorophyll C2 + in Photosynthesis

Cited by 124 publications

References 6 publications

Some photoreactions of spinach chloroplasts in sucrose syrup at high and low temperature

Some photoreactions of spinach chloroplasts in sucrose syrup at high and low temperature

Studies on the red absorption band of chlorophyll a in vivo

Afterglow of chlorophyll in vivo and photosynthesis

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