Electrochromic absorption changes of a chloroplast suspension induced by an external electric field

Schlodder, E.; Witt, H. T.

doi:10.1016/0014-5793(80)80139-6

Cited by 21 publications

(7 citation statements)

References 39 publications

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“…The spectral shifts induced by illumination of the photosynthetic vesicles are believed by most workers to be genuine electrochromic shifts, i.e., to be due to electric field-induced changes in the transition moment of chromophore molecules (Junge, 1977;Witt, 1979;Schlodder and Witt, 1980). It has been shown that the carotenoids consist of two spectrally different pools, only the smaller of which shows a substantial shift upon energization of the membrane (Symons et ai, 1977;De Grooth et al, 1980).…”

Section: Electrochromic Shiftmentioning

confidence: 99%

“…It has been shown that the carotenoids consist of two spectrally different pools, only the smaller of which shows a substantial shift upon energization of the membrane (Symons et ai, 1977;De Grooth et al, 1980). These carotenoids are located near and are polarized by membrane-associated charges (Symons et al, 1977;Sewe and Reich, 1977;Kakitani et al, 1982;De Grooth et al, 1980;Schlodder and Witt, 1980;Witt, 1979) which have been proposed to be in chlorophyll molecules (Sewe and Reich, 1977;Sherman and Clayton, 1972;Matsuura et al, 1980;Webster^ al., 1980). The use of electrochromic shift-related absorbance changes (usually at 518 or 478 nm) for the evaluation of transmembrane electrical fields is hampered by three types of limitations.…”

Section: Electrochromic Shiftmentioning

confidence: 99%

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Determination of the Proton Electrochemical Gradient across Biological Membranes

Azzone

Pietrobon

Zoratti

1984

Current Topics in Bioenergetics

131

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Section: Electrochromic Shiftmentioning

confidence: 99%

Section: Electrochromic Shiftmentioning

confidence: 99%

Determination of the Proton Electrochemical Gradient across Biological Membranes

Azzone

Pietrobon

Zoratti

1984

Current Topics in Bioenergetics

131

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“…A29 reduces to Eq. A25 as in references (10,18,26 2X0Xi which again reduces to Eq. A25 for Am << (Ao, AX).…”

Section: (Al)mentioning

confidence: 99%

Electrophotoluminescence and the electrical properties of the photosynthetic membrane. I. Initial kinetics and the charging capacitance of the membrane

Farkas¹,

Korenstein²,

Malkin³

1984

Biophysical Journal

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Preilluminated chloroplast membranes, and particularly hypotonically swollen vesicles (blebs), give rise to a strong characteristic luminescence (electrophotoluminescence, EPL; Ellenson and Sauer, 1976, Photochem. Photobiol., 23:113-123; Arnold and Azzi, 1971, Photochem. Photobiol., 14:233-240) during the application of a strong external electric field. A detailed kinetic study of EPL was carried out and the initial kinetics from the field onset are reported here. The fast rise time (less than 0.2 mus) of the applied external electric field together with a high instrumental time resolution allowed the observation of a characteristic delay (lag time) between the field onset and the appearance of the induced emission. The lag time decreased with increase in the applied field strength and/or the conductivity of the suspension and is interpreted to be a consequence of (a) the necessity to reach a threshold electrical potential difference in the bleb membrane, below which no emission can be triggered, and (b) the finite time required to attain such a transmembranal field during the charging process of the membrane. A quantitative analysis, connecting the lag time, the controllable experimental parameters, and the membrane electrical characteristics is presented. Its verification was carried out in both size-selected and heterogeneous bleb populations. In the latter, experiments were consistent with the assumption that the lag time reflects the charging of the largest blebs. The results indicate (a) the possibility of directly measuring the specific membrane capacitance, yielding an estimate of Cm = 1.2 +/- 0.3 microF/cm2 (the precision being particle size-homogeneity dependent); (b) A minimal transmembranal potential difference (of approximately 240 mV) is necessary to induce electrophotoluminescence; and (c) the lag duration depends on the time elapsed between the preillumination and the external field application. Correlated with the study of ionophore effects on the lag time, this suggests additivity of the light- and field-induced transmembrane potentials in attaining the threshold for emission.

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“…Therefore, with external electric field pulses of -1000 V/cm a field can be set up across the photosynthetic membrane at least as high as that induced by light (2*105 V cm-', section 3). The relative transmembrane potential difference induced by the external voltage can be followed directly with the quadratic component of the electrochromic absorption changes (see section 3) of the membrane pigments [43] (Fig. 6B).…”

Section: The Transmembrane Electrochemical Proton Potential As Drivinmentioning

confidence: 99%

Primary reactions of oxygenic photosynthesis

Witt

1996

Ber Bunsenges Phys Chem

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Electrochromic absorption changes of a chloroplast suspension induced by an external electric field

Cited by 21 publications

References 39 publications

Determination of the Proton Electrochemical Gradient across Biological Membranes

Determination of the Proton Electrochemical Gradient across Biological Membranes

Electrophotoluminescence and the electrical properties of the photosynthetic membrane. I. Initial kinetics and the charging capacitance of the membrane

Primary reactions of oxygenic photosynthesis

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