Picosecond laser study of fluorescence lifetimes in spinach chloroplast Photosystem I and Photosystem II preparations

Searle, G.F.W.; Barber, James; Harris, L. E.; Porter, George; Tredwell, C.J.

doi:10.1016/0005-2728(77)90040-8

Cited by 59 publications

(14 citation statements)

References 16 publications

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“…The fluorescence yield and lifetime of PS II chlorophyll a are appreciably higher than those of PSI chlorophyll a [11,15]. This can influence the properties of Fn700 and FI715 at room temperature.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the long-wave chlorophyll fluorescence in various green and blue-green algae and diatoms

Goedheer

1981

Photosynth Res

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Two types of long-wave fluorescence bands with similar band shape occur at room temperature in various algae: FII700 and FI715. FII700 occurs in a limited number of algae, follows PS II transients, increases with culture age and is moderately increased by cooling to 83 K. FI715 occurs in most algae, especially Anabaena, but much less in most diatoms and Tribonema. It does not follow PS II transients, does not increase with culture age and is much increased by cooling to 83 K.An interpretation for the characteristics of FII700 and FI715 is given.

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Section: Discussionmentioning

confidence: 99%

Comparison of the long-wave chlorophyll fluorescence in various green and blue-green algae and diatoms

Goedheer

1981

Photosynth Res

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“…A possible explanation for this is that the chlorophyll molecules in these two proteins are on average further apart and that interaction between chlorophylls is less strong than in ChI~-PI. The shorter lifetime for fluorescence from photosystem I at room temperature as compared to photosystem II (27) would then be consistent with a more efficient singlet energy transfer to the photosystem I reaction centre (assuming energy transfer and not trapping to be rate limiting) and a closer average spacing of chlorophyll a molecules in phe~osystem I. In this connection it is of interest that ~,aves of the barley mutant viridis-zb 63 have a lone wavelength emission band even though this mutant lacks photosystem I (12).…”

Section: Norris and Shipman (L 5)mentioning

confidence: 99%

Fluorescence detected magnetic resonance (FDMR) spectroscopy of chlorophyll-proteins from barley

Searle

Koehorst

Schaafsma

et al. 1981

Carlsberg Res. Commun.

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Fluorescence detected magnetic resonance (FDMR) spectra and fluorescence emission spectra at 4.2 K of chlorophyll-proteins isolated and purified from barley thylakoids are presented. The FDMR spectra show the occurrence of chlorophyll a triplet states in all five chlorophyll-proteins studied, namely Chlu-P1, Chla-P2, Chla-P3, Chla/b-Pl and Chla/b-P2.The presence of more than one chlorophyll triplet each associated with a chlorophyll emitting at a specific wavelength gives rise to a characteristic wavelength dependence of the FDM R spectrum of chlorophyll-proteins. The zero field splitting parameters measured, combined with the observed fluorescence emission wavelengths suggest that three types of interactions of the Mg atom of chlorophyll a occur in these proteins: a type similar to that in the parallel dimer (Chl a. H20)2, seen at 721 nm for Chla-PI leading to a positive FDMR signal; a type like that in Chl a-2 pyridine also giving a positive FDMR signal, seen in Chla-P2 and Chla-P3, and a third type similar to that in Chl a. 2H20 leading to a negative FDMR signal, seen for Chla-PI at 679 nm, and for Chla/b-PI and Chla/b-P2.The FDMR spectrum in the antenna of photosystem I (Chla-P1)can probably be ascribed to that of a trap formed by a pair of interacting chlorophyll a molecules, indicating that the organisation of chlorophyll in the antenna may not in principle be very different from that in the photosystem I reaction centre, and that it contains approximately plane-parallel chlorophyll a pairs. Chla-P2 and Chla-P3 do not show a long wavelength (> 700 nm) emission, suggesting a much weaker interaction between chlorophyll molecules in these proteins compared to that in Chla-P1. For Chla/o-Pl and Chla/0-P2 the absence of a long wavelength emission and the observation of zero field splitting (ZFS) parameters similar to that of monomeric Chl a. 2H20 both indicate the absence of strong interactions between chlorophyll a molecules in these proteins also, and it is suggested that chlorophyll a and chlorophyll b molecules occur in interacting pairs. (8,9,26). Since a magnetic field is absent, there is no need to use oriented samples, such as single crystals, in order to obtain magnetic resonance spectra with satisfactory resolution (-10-2). In addition, optical detection of magnetic resonance transitions is well-known to be very sensitive as compared with detection of microwave-absorption by diodes or bolometers, such as in conventional high-field electron paramagnetic resonance (EPR) spectroscopy (1 I). This combination of properties makes FDMR spectroscopy an ideal technique for studying complex systems, such as the chlorophyll-proteins of a photosynthetic membrane which can be obtained only in limited amounts and in non-oriented form.Triplet state FDMR spectroscopy makes use of the fact, that the three-fold degeneracy of the molecular triplet state is lifted by spin-spin interaction, even in the absence of an external magnetic field. For photosynthetic pigments, the resulting zero field splittings (ZFS) are 10-2cm...

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“…This yielded an average value of 650 ± 150 psec, in good agreement with results from phase-shift measurements. Several research groups (18,20,39,45,94,102) have noted that in experiments in which the entire pulse trains were used for excitation, singlet-triplet fu sion processes can determine the observed fluorescence lifetimes. Triplet excitons, fo rmed by intersystem crossing from singlet excitons, live longer in vivo than the interval between pulses (typically 6.7-10 nsec).…”

Section: Picosecond Measurementsmentioning

confidence: 99%

“…(b) Photon density was high, greater than 5 X 1015 photons cm-2, and the decay curve can be fit by a tll2 expression (102).…”

Section: Picosecond Measurementsmentioning

confidence: 99%

“…However, the intensity dependence of the fluorescence quantum efficiency has been used recently to explore the organization of the photosynthetic units fr om several strains of photosynthetic bacteria (17). Recent studies have shown that picosecond techniques can be useful in measuring fluorescence lifetimes in biological systems if care is taken in choosing the mode and intensity of excitation (IS,20,45,94,102).…”

Section: Introductionmentioning

confidence: 99%

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Picosecond Flash Photolysis in Biology and Biophysics

Holten¹,

Windsor²

1978

Annu. Rev. Biophys. Bioeng.

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Three years ago one of us was asked by a funding agency to dust off his crystal ball and assess the fu ture importance of picosecond studies to chemistry. After a careful "objective" review of what had been accomplished up to then, and trying hard not to appear self-serving, he boldly concluded that a modest increase in the level of fu nding for picosecond instrumental developments appeared to be justified. In the light of what has occurred since then, this recommendation can only be considered cowardly. Almost all application of picosecond techniques in biology and biophysics has taken place in the past 2 or 3 years. Valuable new insights have been gained and in some areas, notably photosynthesis, striking ad vances in understanding have been made. Why? What special magic do picosecond techniques hold for biology? To answer this question we must trace its roots back to chemistry. The vast majority of chemical and biochemical reactions are composed of many elementary steps. The primary steps, which involve energy migration, bond breakage, molecular rearrangements, and charge transfer, all occur in the time range fr om about 10-14 to 10-8 sec. The "slowness" of an overall reaction is usually determined by other considerations, such as steric fa ctors and diffusion of reactants to the site of reaction. Picosecond spectroscopy enables us for the fi rst time to take a look at these primary steps.In this review we fo cus on the new insights that picosecond studies have provided in several important areas of biology. The area that has received the greatest emphasis to date is photosynthesis, which undoubtedly is appropriate, since we are all dependent upon photosynthesis both for our origin and for our continued survival. Picosecond fluorescence studies in both plants and bacteria show that excitation energy migrates fr om the antenna or light-harvesting system to the . reaction center in times that range fr om 10 psec to about I nsec, depending upon 189

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Picosecond laser study of fluorescence lifetimes in spinach chloroplast Photosystem I and Photosystem II preparations

Cited by 59 publications

References 16 publications

Comparison of the long-wave chlorophyll fluorescence in various green and blue-green algae and diatoms

Comparison of the long-wave chlorophyll fluorescence in various green and blue-green algae and diatoms

Fluorescence detected magnetic resonance (FDMR) spectroscopy of chlorophyll-proteins from barley

Picosecond Flash Photolysis in Biology and Biophysics

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