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  • 1
    Electronic Resource
    Electronic Resource
    Additive decomposition for the product of two θ3 functions and modular equations (1989)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 30 (1989), S. 2012-2015 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: By using a general additive decomposition for the product of two θ3 functions, a simple and unified derivation of the modular equations of degree 3, 5, and 7 is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528238
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  • 2
    Electronic Resource
    Electronic Resource
    A Thermal Broadening Analysis of Absorption Spectra of the D1/D2/Cytochrome b-559 Complex in Terms of Gaussian Decomposition Sub-bands (1995)
    s.l. : American Chemical Society
    Biochemistry 34 (1995), S. 15267-15275 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00046a035
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  • 3
    Electronic Resource
    Electronic Resource
    Gaussian Decomposition of Absorption and Linear Dichroism Spectra of Outer Antenna Complexes of Photosystem II (1994)
    s.l. : American Chemical Society
    Biochemistry 33 (1994), S. 8982-8990 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00196a016
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  • 4
    Electronic Resource
    Electronic Resource
    Distribution of the chlorophyll spectral forms in the chlorophyll-protein complexes of photosystem II antenna (1993)
    s.l. : American Chemical Society
    Biochemistry 32 (1993), S. 3203-3210 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00064a002
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  • 5
    Electronic Resource
    Electronic Resource
    Model studies on the excited state equilibrium perturbation due to reaction centre trapping in Photosystem I (1997)
    Springer
    Photosynthesis research 52 (1997), S. 245-253 
    Details
    ISSN: 1573-5079
    Keywords: core chlorophyll molecules ; excited state equilibrium perturbation ; model studies ; Photosystem I ; primary photochemical rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fluorescence yield for 694 nm excitation in a Photosystem I-200 particle is significantly lower than that for 665 nm excitation. This supports the previous suggestion, based on a thermodynamic analysis of absorption and emission spectra, that thermal equilibration in the 690–700 nm spectral interval is perturbed, presumably by primary photochemistry [Croce et al. (1996) Biochem 35: 8572–8579]. This equilibrium perturbation was used in the present study as a novel fit parameter in numerical simulations aimed at describing the kinetic/thermodynamic properties of exciton flow and primary photochemistry in PS I. To this end a four energy level scheme was developed which satisfactorily described all the fit parameters, including that of the equilibrium perturbation. An important characteristic which distinguished this model from other model studies is the presence of a number of chlorophyll molecules with absorption maximum near 695 nm, tightly coupled to P700. The main conclusions are: (I) about six chlorophyll molecules absorbing near 695 nm are tightly coupled to P700, in close agreement with the recent crystallographic structure for the Photosystem I core [Krauß et al. (1996); Nature Struct Biol 3: 965–973]; (II) energy transfer from the bulk pigments to the P700 core pigments is slow; (III) analysis of the most physically straightforward model indicates that the primary photochemical charge separation rate is very high (kpc ≥ 2.5 ps-1), though it is possible to simulate the equilibrium perturbation with lower kpc values assuming a large free energy decrease in the excited state of P700; (IV) the red spectral forms slow down reaction centre trapping by a 2–3 fold factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005826924445
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  • 6
    Electronic Resource
    Electronic Resource
    Studies on light absorption and photochemical activity changes in chloroplast suspensions and leaves due to light scattering and light filtration across chloroplast and vegetation layers (1989)
    Springer
    Photosynthesis research 20 (1989), S. 207-220 
    Details
    ISSN: 1573-5079
    Keywords: chloroplasts ; detour effect ; leaves ; light absorption ; light filtration ; photosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An experimental analysis is presented concerning the effect on relative light absorption by the two photosystems caused by (a) a highly light scattering environment (the “detour effect”) and (b) light filtration across successive chloroplast layers (the “light attenuation effect”). Both suspensions of isolated chloroplasts and leaves were employed. It is concluded that within a single spinach leaf these phenomena are likely to lead to only rather small increases in relative photosystem I absorption and activity with respect to photosystem II and will thus not exert a significant effect on non cyclic electron transport. On the contrary when light is filtrated across successive vegetation layers (shade light) significant increases in the relative PSI absorption and activity may be encountered. It is determined that the “detour effect” in mature leaves from a variety of plants increases overall photosynthetically useful light absorption by 35–40%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034065
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  • 7
    Electronic Resource
    Electronic Resource
    Light-induced fluorescence quenching in the light-harvesting chlorophyll a/b protein complex (1991)
    Springer
    Photosynthesis research 27 (1991), S. 57-64 
    Details
    ISSN: 1573-5079
    Keywords: Light-harvesting chlorophyll a/b protein complex II ; light-induced fluorescence quenching ; spinach thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Irradiation of the principal photosystem II light-harvesting chlorophyll-protein antenna complex, LHC II, with high light intensities brings about a pronounced quenching of the chlorophyll fluorescence. Illumination of isolated thylakoids with high light intensities generates the formation of quenching centres within LHC II in vivo, as demonstrated by fluorescence excitation spectroscopy. In the isolated complex it is demonstrated that the light-induced fluorescence quenching: a) shows a partial, biphasic reversibility in the dark; b) is approximately proportional to the light intensity; c) is almost independent of temperature in the range 0–30°C; d) is substantially insensitive to protein modifying reagents and treatments; e) occurs in the absence of oxygen. A possible physiological importance of the phenomenon is discussed in terms of a mechanism capable of dissipating excess excitation energy within the photosystem II antenna.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029976
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  • 8
    Electronic Resource
    Electronic Resource
    Gaussian band analysis of absorption, fluorescence and photobleaching difference spectra of D1/D2/cytb-559 complex (1994)
    Springer
    Photosynthesis research 41 (1994), S. 465-473 
    Details
    ISSN: 1573-5079
    Keywords: Photosystem II ; reaction centres ; spectral decompositions ; P680 ; pheophytin ; homogeneous ; inhomogeneous band broadening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study of the absorption and fluorescence characteristics of the D1/D2/cytb-559 reaction centre complex of Photosystem II has been carried out by gaussian decomposition of absorption spectra both at room temperature and 72 K and of the room temperature fluorescence spectrum. A five component fit was found in which the absorption and fluorescence sub-bands could be connected by the Stepanov relation. The photobleaching and light-activated degradation in the dark of long wavelength pigments permitted a further characterisation of the absorption bands. The absorption (fluorescence) maxima of the five bands at room temperature are 660 nm (670 nm), 669 nm (675 nm), 675 nm (681 nm), 680 nm (683 nm), 681 nm (689 nm). A novel feature of this analysis is the presence of two approximately isoenergetic absorption bands near 680 nm at room temperature. The narrower one (FWHM=12.5 nm) is attributed to pheophytin while the broader band (FWHM=23 nm) is thought to be P680. The P680 band width is discussed in terms of homogeneous and site inhomogeous band broadening. The P680 fluorescence has a large Stokes shift (≈9 nm) and most fluorescence in the 690–700 nm range is associated with this chromophore. The three accessory pigment bands are broad (FWHM=17–24 nm) and the 660 nm gaussian is largely temperature insensitive thus indicating significant site inhomogeneous broadening. The very slight narrowing of the D1/D2/cytb-559 Qy absorption at crytogenic temperatures is discussed in terms of the coarse spectral inhomogeneity associated with the spectral forms and the apparently large site inhomogeneous broadening of short wavelength accessory pigments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183048
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  • 9
    Electronic Resource
    Electronic Resource
    Slow exciton trapping in Photosystem II: A possible physiological role (1996)
    Springer
    Photosynthesis research 47 (1996), S. 167-173 
    Details
    ISSN: 1573-5079
    Keywords: antenna-trap equilibration ; photoinhibition ; photoprotection ; Photosystem II ; trapping time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosystem II, which has a primary photochemical charge separation time of about 300 ps, is the slowest trapping of all photosystems. On the basis of an analysis of data from the literature this is shown to be due to a number of partly independent factors: a shallow energy funnel in the antenna, an energetically shallow trap, exciton dynamics which are partly ‘trap limited’ and a large antenna. It is argued that the first three of these properties of Photosystem II can be understood in terms of protective mechanisms against photoinhibition. These protective mechanisms, based on the generation of non photochemical quenching states mostly in the peripheral antenna, are able to decrease pheophytin reduction under conditions in which the primary quinone, QA, is already reduced, due to the slow trapping properties. The shallow antenna funnel is important in allowing quenching state-protective mechanisms in the peripheral antenna.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016179
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  • 10
    Electronic Resource
    Electronic Resource
    The importance of PS I chlorophyll red forms in light-harvesting by leaves (1999)
    Springer
    Photosynthesis research 60 (1999), S. 209-215 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast ; light absorption ; light environment ; optical cross-section ; photosystem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have investigated the importance of the long wavelength absorbing spectral forms (red forms) of Photosystem I in photosynthetic light harvesting by leaves. To this end leaf spectra were simulated by using a linear combination of absorption (OD) spectra of purified Photosystem I, Photosystem II and LHC II, multiplied by an empirical multiple scattering chloroplast/leaf conversion function. In this way it is demonstrated that while the PS I red forms account for only about 4–5% of light absorption in a normal ‘daylight’ environment, in different ‘shadelight’ environments these long wavelength pigments may be responsible for up to 40% of total photon capture. In the context of maximising the photosynthetic quantum efficiency under the low light conditions of ‘shadelight’, this relative increase in the absorption cross section of PS I can be understood by considering the increased synthesis of the major PS II antenna complex, LHC II, known to occur in plants growing under these light conditions. It is demonstrated that for plants in a moderate to deep ‘shadelight’ regime the PS II cross section needs to increase by 50% to 100% via LHC II synthesis to balance the increased PS I absorption by the red forms. The possibility that under ‘shade light’ conditions the increased PS I cross section may serve in cyclic phosphorylation is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006236829711
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