In chloroplasts of plants and algae, state transition is an important regulatory mechanism to maintain the excitation balance between PSI PSII in thylakoid membrane. Light-harvesting complex II (LHCII) plays a key role as regulated energy distributor PSII. It widely accepted that LHCII, which bound localized mainly granal thylakoid, migrates bind with stroma-exposed under preferential The phenomena have been extensively characterized by many methods. However, exchange LHCII has not directly...

The rate of the electron transfer reaction from reduced primary acceptor chlorophyll a (A0-) to secondary quinone (Q) was measured by picosecond−nanosecond laser spectroscopy at 280 K in photosynthetic center (RC) complex plant photosystem I (PS I). free energy change (ΔG0) varied between −1.1 and +0.2 eV reconstitution 13 different quinone/quinonoid compounds after extraction intrinsic phylloquinone. Phylloquinone its natural analog menaquinone, both which show ΔG0 value −0.34 eV, gave...

Comparison of the steady-state FTIR absorption spectra coumarin-102 (C-102) in tetrachloroethylene with added aniline various concentrations, neat and N,N-dimethylaniline (DMA), indicates formation a hydrogen-bonded complex between C-102 solution. Subpicosecond time-resolved infrared spectroscopy has been applied to study dynamics hydrogen-bond following photoexcitation chromophore C-102−aniline complex. Upon at 400 nm, hydrogen bond breaks within 250 fs. Reformation excited molecule takes...

In this study, we produced selective images of photosystems in plant chloroplasts situ. We used a spectroimaging microscope, equipped with near-infrared (NIR) laser that provided light at wavelengths mainly between 800 and 830 nm, to analyze chlorophyll autofluorescence spectra from leaves Zea mays room temperature. Femtosecond excitation mesophyll cells revealed spectral shape was attributable PSII its antenna the centers grana spots. found continuous wave emitted by NIR wavelength as long...

Abstract Some filamentous cyanobacteria carry out oxygenic photosynthesis in vegetative cells and nitrogen fixation specialized known as heterocysts. Thylakoid membranes contain photosystem I (PSI) PSII, while those heterocysts predominantly PSI. Therefore, the thylakoid change drastically when differentiating from a cell into heterocyst. The dynamics of these changes have not been sufficiently characterized situ. Here, we used time-lapse fluorescence microspectroscopy to analyze Anabaena...

Microscopic autofluorescence spectral imaging of chloroplasts in maize mesophyll cells using near-infrared laser excitation has previously shown that a photosystem I component exhibits an intensity similar to II at ∼294 K when continuous-wave 800−820 nm is used. To establish the generality this phenomenon, Parachlorella kessleri (P. kessleri) were studied. A 785 promoted photosystem-I-specific fluorescence P. chloroplasts. The difference chlorophyll peak wavelengths between and correlated...

CooA from Rhodospirillum rubrum is a transcriptional activator in which heme prosthetic group acts as CO sensor and regulates the activity of protein. In this study, electronic relaxation heme, concurrent recombination between ligands at ∼280 K were examined an effort to understand environment around dynamics ligands. Upon photoexcitation reduced 400 nm, occurred with time constants 0.8 1.7 ps. The ligand rebinding was substantially completed constant 6.5 ps, followed by slow process 173...

Transient absorption spectroscopy has been used to study sub-picosecond energy transfer processes in isolated photosystem II (PS II) reaction centers. As reported previously [Durrant, J. R.; et al. Proc. Natl. Acad. Sci. U.S.A. 1992, 89, 11632−11636], using long wavelength (694 nm) excitation, spectral evolution of the isotropic Qy band bleach/stimulated emission is dominated by with a 100 ± 50 fs time constant. In contrast, depolarization this signal occurs constant 400 30 fs, from an...

Summary We describe the construction and characterization of a laser‐line‐scanning microscope capable detection broad fluorescence spectra with resolution 1 nm. A near‐infrared femtosecond pulse train at 800 nm was illuminated on line (one lateral axis, denoted as X axis) in specimen by resonant scanning mirror oscillating 7.9 kHz, total multi‐photon–induced from linear region focused slit an imaging polychromator. An electron‐multiplying CCD camera used to resolve different colours...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRates of Primary Electron Transfer Reactions in the Photosystem I Reaction Center Reconstituted with Different Quinones as Secondary AcceptorShigeichi Kumazaki, Masayo Iwaki, Isamu Ikegami, Hideki Kandori, Keitaro Yoshihara, and Shigeru ItohCite this: J. Phys. Chem. 1994, 98, 43, 11220–11225Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October...

Primary photochemistry in photosystem I (PS I) reaction center complex from Acaryochloris marina that uses chlorophyll d instead of a has been studied with femtosecond spectroscopy. Upon excitation at 630 nm, almost full equilibration among antenna chlorophylls and 40% the quenching by are completed time constants 0.6(±0.1) 4.9(±0.6) ps, respectively. The rise decay primary charge‐separated state proceed apparent 7.2(±0.9) 50(±10) suggesting reduction electron acceptor (A 0 ) its reoxidation...

Femtosecond transient absorption spectroscopy was applied to the photosystem I reaction center particles containing only 12−13 chlorophylls per primary electron donor chlorophyll (P700), which were prepared from spinach. Upon preferential excitation of P700, an band due excited state P700 newly observed in 730−750 nm region. The charge separation dynamics at ≈280 K revealed by rise radical pair chlorophylls. biphasic: 0.8 ps (50%) and 9 (50%). component is fastest phase ever center. On basis...

In only a few picoseconds the photoinduced electron transfer in noncovalently linked complex between zinc porphyrin 1 and quinone 2 is complete. Transient absorption spectra show cation radical as typical intermediate of transfer.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPrimary Photochemical Processes in P700-Enriched Photosystem I Particles: Trap-Limited Excitation Decay and Primary Charge SeparationShigeichi Kumazaki, Hideki Kandori, Hrvoje Petek, Keitaro Yoshihara, Isamu IkegamiCite this: J. Phys. Chem. 1994, 98, 40, 10335–10342Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://doi.org/10.1021/j100091a057RIGHTS & PERMISSIONSArticle...

CooA, which is a transcriptional regulator heme protein allosterically triggered by CO, studied femtosecond visible-pump mid-IR-probe spectroscopy. Transient bleaching upon excitation of the in Soret band detected at ∼1979 cm-1, absorption region CO bound to heme. The bleach signal shows nonexponential decay with time constants 56 and 290 ps, caused rebinding About 98% dissociated recombines geminately. geminate recombination rate CooA significantly faster than those myoglobin hemoglobin....

Deuterium isotope effect on the solvation dynamics is observed in system of aniline (AN) as a solvent for first time by dynamic Stokes shift method. Perdeuterated AN (AN–d7) or amino deuterated (AN–d2) shows slower than normal AN. N,N–dimethylaniline (DMA) also studied and there no process. The differences between DMA are proposed to be related presence absence intermolecular hydrogen bondings.

Radiationless deactivation of 2-piperidinoanthraquinone (2PAQ) in its excited singlet state induced by an intermolecular hydrogen bond interaction was studied picosecond and femtosecond transient absorption spectroscopy benzene. On addition alcohol, the 2PAQ exhibited a blue shift effectively quenched. Kinetic analyses decay obtained experiments using pulse compared well with those from dynamic fluorescence studies; observed confirmed as being attributed to 2PAQ. Subpicosecond indicated that...

Spectral sensitization and supersensitization of the silver bromide nanocrystals were studied by femtosecond fluorescence up-conversion technique. An annihilation-free from J-aggregates Dye 1 (3,3'-disulfopropyl-5,5'-dichloro-9-ethylthiacarbocyanine) adsorbed on (edge-to-edge distance 40 to 900 nm) different shapes (cubic octahedral) was measured. Very fast nonexponential decays observed with a component 0.4 2.5 ps, an average decay time 1.1 5.5 depending type size AgBr grains. The is...