Papers by Ryszard Jankowiak
The journal of physical chemistry. B, Jan 2, 2017
The B800-850 LH2 antenna from the photosynthetic purple sulfur bacterium Allochromatium vinosum e... more The B800-850 LH2 antenna from the photosynthetic purple sulfur bacterium Allochromatium vinosum exhibits an unusual spectral splitting of the B800 absorption band; i.e., two bands are well-resolved at 5 K with maxima at 805 nm (B800R) and 792 nm (B800B). To provide more insight into the nature of the B800 bacteriochlorophyll (BChl) a molecules, high-resolution hole-burning (HB) spectroscopy is employed. Both white light illumination and selective laser excitations into B800R or B800B lead to B800R → B800B phototransformation. Selective excitation into B800B leads to uncorrelated excitation energy transfer (EET) to B800R and subsequent B800R → B800B phototransformation. The B800B → B800R EET time is 0.9 ± 0.1 ps. Excitation at 808.4 nm (into the low-energy side of B800R) shows that the lower limit of B800R → B850 EET is about 2 ps, as the B800R → B800B phototransformation process could contribute to the corresponding zero-phonon hole width. The phototransformation of B800R leads to a...
Journal of The Royal Society Interface, 2019
The Fenna–Matthews–Olson (FMO) light-harvesting antenna protein of green sulfur bacteria is a lon... more The Fenna–Matthews–Olson (FMO) light-harvesting antenna protein of green sulfur bacteria is a long-studied pigment–protein complex which funnels energy from the chlorosome to the reaction centre where photochemistry takes place. The structure of the FMO protein from Chlorobaculum tepidum is known as a homotrimeric complex containing eight bacteriochlorophyll a per monomer. Owing to this structure FMO has strong intra-monomer and weak inter-monomer electronic coupling constants. While long-lived (sub-picosecond) coherences within a monomer have been a prevalent topic of study over the past decade, various experimental evidence supports the presence of subsequent inter-monomer energy transfer on a picosecond time scale. The latter has been neglected by most authors in recent years by considering only sub-picosecond time scales or assuming that the inter-monomer coupling between low-energy states is too weak to warrant consideration of the entire trimer. However, Förster theory predict...
The journal of physical chemistry. B, Jan 4, 2017
Identification of the lowest energy pigments in the photosynthetic CP47 antenna protein complex o... more Identification of the lowest energy pigments in the photosynthetic CP47 antenna protein complex of Photosystem II (PSII) is essential for understanding its excitonic structure, as well as excitation energy pathways in the PSII core complex. Unfortunately, there is no consensus concerning the nature of the low-energy state(s), nor chlorophyll (Chl) site energies in this important photosynthetic antenna. Although we raised concerns regarding the estimations of Chl site energies obtained from modeling studies of various types of CP47 optical spectra [Reinot, T; et al., Anal. Chem. Insights 2016, 11, 35-48] recent new assignments imposed by the shape of the circularly polarized luminescence (CPL) spectrum [Hall, J.; et al., Biochim. Biophys. Acta 2016, 1857, 1580-1593] necessitate our comments. We demonstrate that other combinations of low-energy Chls provide equally good or improved simultaneous fits of various optical spectra (absorption, emission, CPL, circular dichroism, and nonreso...
The Journal of Physical Chemistry B, 2006
Results are presented of nonphotochemical hole-burning (HB) experiments on cancerous ovarian and ... more Results are presented of nonphotochemical hole-burning (HB) experiments on cancerous ovarian and analogous normal peritoneal in vitro tissues stained with the mitochondrial-selective dye rhodamine 800. A comparison of fluorescence excitation spectra, hole-growth kinetics data, and external electric field (Stark) effects on the shape of spectral holes burned in cancerous and normal tissues stained with rhodamine 800 revealed significant differences only in the dipole moment change (fDeltamu) measured by a combination of HB and Stark spectroscopies. It is shown that the permanent dipole moment change for the S0--> S1 transition of the rhodamine 800 molecules in cancerous tissue is higher than that of normal tissue by a factor of about 1.4. The finding is similar to the HB results obtained earlier for human ovarian surface epithelial cell lines, i.e., OV167 carcinoma and OSE(tsT)-14 normal cells stained with the same mitochondria-specific dye (Walsh et al. Biophys. J. 2003, 84, 1299). We propose that the observed difference in the permanent dipole moment change in cancerous ovarian tissue is related to a modification in mitochondrial membrane potential.
Chemical Sciences Journal, 2017
Low temperature (high-resolution) hole-burning (HB) spectroscopy and modeling studies of various ... more Low temperature (high-resolution) hole-burning (HB) spectroscopy and modeling studies of various optical spectra of photosynthetic complexes provide new insight into excited state electronic structure and dynamics. The following complexes will be briefly discussed: 1) The CsmAbacteriochlorophyll a complex from C. tepidum. In this case, in contrast to literature data, an alternative structure is proposed for the baseplate; 2) The FMO antenna complex from C. tepidum and its mutants. Using an experimentally determined shape for the spectral density for the lowestenergy state (Jph(ω)), simulated optical spectra are obtained from structure-based calculations for the FMO trimer. For higher energy pigments, the effect of a broader Jph(ω) shape with a different S factor and/or variable inh are also tested for comparison. I will demonstrate that in order to properly describe various low-temperature optical spectra, a downward uncorrelated excitation energy transfer (EET) between trimer subunits must to be taken into account. That is, after light induced coherences vanish within each monomer, uncorrelated EET between the lowest exciton levels of each monomer takes place due to static structural inhomogeneities in the trimer. The information gained provides new insight into disorder, excitonic structure, EET dynamics and mutation induced changes induced via site directed mutagenesis; and 3) The B800-850 LH2 antenna complex from Alc.vinosum, which exhibits an unusual spectral splitting of the B800 absorption band. Here, we propose that various protein conformations lead to either strong or weak hydrogen bonds between the protein and B800 pigments.
Chemical Physics, 1995
Spectral hole burning is used to study the pressure dependence of the Qy absorption spectrum and ... more Spectral hole burning is used to study the pressure dependence of the Qy absorption spectrum and primary charge separation kinetics of the D1-D2-cyt b559 reaction center complex of photosystem II. The 4.2 K lifetime of P680 *, the primary donor state, lengthens from 2.0 ps at 0.1 MPa to 7.0 ps at 267 MPa. Importantly, this effect is irreversible (plastic), in sharp contrast with the elastic effects of pressure on the low-temperature absorption and non-line-narrowed hole spectrum of P680. These observations and data which show that the electron-phonon coupling is weakly dependent on pressure, suggest a model that has the plastic behavior of charge separation kinetics due mainly to the pressure dependence of the energy of the acceptor state and of the variance of the P680 *-acceptor energy gap stemming from structural heterogeneity. Nonadiabatic rate expressions, which take into account the distribution of energy gap values, are used to estimate the linear pressure shift of the acceptor state energy for both the superexchange and two-step mechanisms for primary charge separation. For both mechanisms shifts in the vicinity of 1 cm-1/MPa are required to explain the data, a value which is not unreasonable based on pressure dependent studies of other systems. The results point to the marriage of hole burning and high pressures as having considerable potential for the study of primary transport dynamics in reaction center and antenna complexes.
Advanced Materials Interfaces, 2016
Here the study of effects of plasmonic nanoparticles (PNPs) conjugated with natural extract light... more Here the study of effects of plasmonic nanoparticles (PNPs) conjugated with natural extract light‐harvesting complex II (LHCII) is reported. Three types of core–shell metal@TiO2 PNPs with distinct surface plasmonic resonance are prepared. The plasmonic adsorption of the metal core provides strong photon capture and enhances the LHCII excitation through plasmon‐induced resonance energy transfer (PIRET). More efficient charge separation is facilitated at LHCII/TiO2 interface as revealed by quenching of the fluorescence and reduction of the fluorescence lifetime of LHCII after adsorbing on PNPs. Femtosecond transient absorption provides further conclusive proof for charge injection from excited LHCII into the TiO2 conduction band. The plasmonic effects are further demonstrated in the enhanced photovoltaic properties after incorporating the PNPs in LHCII‐sensitized solar cells built on a 3D TiO2 nanotree photoanode. The photocurrent is enhanced by all PNPs under illumination of the full solar spectrum and the selected wavelength windows around Soret and Q bands of LHCII trimer, and the “dark region” between them. This study reveals that the core–shell PNPs can enhance the LHCII‐sensitized solar cells based on multiple mechanisms, including enhancing light harvesting, promoting PIRET from PNP to LHCII, and facilitating charge injection from excited LHCII into TiO2.
Photosynthesis Research, 2014
The Fenna-Matthews-Olson (FMO) complex from the green sulfur bacterium Chlorobaculum tepidum was ... more The Fenna-Matthews-Olson (FMO) complex from the green sulfur bacterium Chlorobaculum tepidum was studied with respect to its stability. We provide a critical assessment of published and recently measured optical spectra. FMO complexes were found to destabilize over time producing spectral shifts, with destabilized samples having significantly higher hole-burning efficiencies; indicating a remodeled protein energy landscape. Observed correlated peak shifts near 825 and 815 nm suggest possible correlated (protein) fluctuations. It is proposed that the value of 35 cm(-1) widely used for reorganization energy (E λ ), which has important implications for the contributions to the coherence rate (Kreisbeck and Kramer 3:2828-2833, 2012), in various modeling studies of two-dimensional electronic spectra is overestimated. We demonstrate that the value of E λ is most likely about 15-22 cm(-1) and suggest that spectra reported in the literature (often measured on different FMO samples) exhibit varied peak positions due to different purification/isolation procedures or destabilization effects.
The Journal of Physical Chemistry B, 2014
We present an improved simulation methodology to describe nonphotochemical hole-burned (NPHB) spe... more We present an improved simulation methodology to describe nonphotochemical hole-burned (NPHB) spectra. The model, which includes both frequency-dependent excitation energy transfer (EET) rate distributions and burning following EET, provides reasonable fits of various optical spectra including resonant and nonresonant holes in the case of FMO complex. A qualitative description of the NPHB process in light of a very complex protein energy landscape is briefly discussed. As an example, we show that both resonant and nonresonant HB spectra obtained for the 825 nm band of the trimeric FMO of C. tepidum are consistent with the presence of a relatively slow EET between the lowest energy states of the monomers of the trimer (mostly localized on BChl a 3), with a weak (∼1 cm(-1)) coupling between these states revealed via calculated emission spectra. We argue that the nature of the so-called 825 nm absorption band of the FMO trimer, contrary to the presently accepted consensus, cannot be explained by a single transition.
physica status solidi (b), 1984
ABSTRACT
The Journal of Physical Chemistry Letters, 2015
In the photosynthetic green sulfur bacterium Chlorobaculum tepidum, the baseplate mediates excita... more In the photosynthetic green sulfur bacterium Chlorobaculum tepidum, the baseplate mediates excitation energy transfer from the light-harvesting chlorosome to the Fenna-Matthews-Olson (FMO) complex and subsequently toward the reaction center (RC). Literature data suggest that the baseplate is a 2D lattice of BChl a-CsmA dimers. However, recently, it has been proposed, using 2D electronic spectroscopy (2DES) at 77 K, that at least four excitonically coupled BChl a are in close contact within the baseplate structure [ Dostál , J. ; et al., J. Phys. Chem. Lett. 2014 , 5 , 1743 ]. This finding is tested via hole burning (HB) spectroscopy (5 K). Our results indicate that the four excitonic states identified by 2DES likely correspond to contamination of the baseplate with the FMO antenna and possibly the RC. In contrast, HB reveals a different excitonic structure of the baseplate chromophores, where excitation is transferred to a localized trap state near 818 nm via exciton hopping, which leads to emission near 826 nm.
Using hole-burning spectroscopy, we show that excitation energy transfer (EET) time in ethynyl-li... more Using hole-burning spectroscopy, we show that excitation energy transfer (EET) time in ethynyl-linked chlorophyll trefoil (ChlT1) monomer is very fast (∼2.5 ps) at liquid helium temperature. This is consistent with data obtained by femtosecond transient spectroscopy experiments performed at room temperature, in which an EET time of 1.8 ps was observed (Kelley, R. F. et al. Angew. Chem. Int. Ed. 2006, 45, 7979). This finding further supports the importance of through-bond electronic coupling at low temperature. In addition, we show that ChlT1 (even at very low concentrations) in methyl tetrahydrofuran-ethanol glass (1:200 v/v; T ∼ 5 K) forms different types of aggregates. It is demonstrated that the relative distribution of various types of aggregates (whose possible structures are briefly discussed) depends on the cooling rate and matrix composition. For example, the EET time in two types of ChlT1-based aggregates is slower by a factor of ∼5-7 with respect to that observed for ChlT1 monomer. This indicates that ChlT1 aggregates can retain ultrafast energy transfer properties similar to those observed in natural photosynthetic antennas. It is anticipated that such building blocks could be utilized in future photovoltaic devices.
Chemical Research in Toxicology, 1999
Chemical Research in Toxicology, 1999
The DNA adducts of benzo[a]pyrene (BP) formed in vitro were previously identified and quantitated... more The DNA adducts of benzo[a]pyrene (BP) formed in vitro were previously identified and quantitated. In this paper, we report the identification and quantitation of the depurination adducts of BP, 8-(benzo[a]pyrene-6-yl)guanine (BP-6-C8Gua), BP-6-N7Gua, and BP-6-N7Ade, formed in mouse skin by one-electron oxidation, as well as the major stable adduct formed via the diolepoxide pathway, BP diolepoxide bound at C-10 to the
Chemical Research in Toxicology, 1999
The journal of physical chemistry. B, Apr 12, 2018
We report high-resolution (low-temperature) absorption, emission, and nonresonant/resonant hole-b... more We report high-resolution (low-temperature) absorption, emission, and nonresonant/resonant hole-burned (HB) spectra and results of excitonic calculations using a non-Markovian reduced density matrix theory (with an improved algorithm for parameter optimization in heterogeneous samples) obtained for the Y16F mutant of the Fenna-Matthews-Olson (FMO) trimer from the green sulfur bacterium Chlorobium tepidum. We show that the Y16F mutant is a mixture of FMO complexes with three independent low-energy traps (located near 817, 821, and 826 nm), in agreement with measured composite emission and HB spectra. Two of these traps belong to mutated FMO subpopulations characterized by significantly modified low-energy excitonic states. Hamiltonians for the two major subpopulations (Sub and Sub) provide new insight into extensive changes induced by the single-point mutation in the vicinity of BChl 3 (where tyrosine Y16 was replaced with phenylalanine F16). The average decay time(s) from the higher...
The Journal of Physical Chemistry
The Journal of Physical Chemistry
A formalism for calculating the density of states (DOS) function for tunneling systems in amorpho... more A formalism for calculating the density of states (DOS) function for tunneling systems in amorphous materials is described. Gaussian distribution functions for the asymmetry (..delta..) and the tunneling parameter (lambda) are employed. It is shown that over a broad energy range (E << planck's constant omegaâ) the DOS function is an increasing function of energy proportional to E/sup ..mu../sub eff//
The Journal of Physical Chemistry
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Papers by Ryszard Jankowiak