The photoactivation dynamics of two new flavoproteins (OtCPF1 and OtCPF2) the cryptochrome photolyase family (CPF), belonging to green alga Ostreococcus tauri, was studied by broadband UV−vis femtosecond absorption spectroscopy. Upon excitation protein chromophoric cofactor, flavin adenine dinucleotide in its oxidized form (FADox), we observed both cases ultrafast photoreduction FADox: 390 fs for OtCPF1 590 OtCPF2. Although such electron transfer has already been reported other CPF members,...

The animal-like cryptochrome of Chlamydomonas reinhardtii (CraCRY) is a recently discovered photoreceptor that controls the transcriptional profile and sexual life cycle this alga by both blue red light. CraCRY has uncommon feature efficient formation longevity semireduced neutral form its FAD cofactor upon light illumination. Tyrosine Y373 plays crucial role elongating , as fourth member, electron transfer (ET) chain found in most other cryptochromes DNA photolyases, which comprises...

Dronpa is a photochromic green fluorescent protein (GFP) homologue used as probe in super-resolution microscopy. It known that the reaction involves cis/trans isomerization of chromophore and protonation/deprotonation its phenol group, but sequence time two steps their characteristic scales are still subject much debate. We report here comprehensive UV-visible transient absorption spectroscopy study photoactivation mechanism Dronpa, covering all relevant from ∼100 fs to milliseconds. The...

The ultrafast photophysics of oxidized and reduced flavin adenine dinucleotide (FAD) in aqueous solution was studied by broadband UV−vis femtosecond transient absorption spectroscopy. We observed that FAD (FADox) readily aggregates at submillimolar concentration. Upon excitation FADox, three excited-state lifetimes were found assigned to different species: the closed (stacked) conformation monomer (∼5.4 ps), open (extended) (∼2.8 ns), dimer (∼27 ps). In case stacked monomer, we show...

Photolyases are flavoenzymes repairing UV-induced lesions in DNA, which may be activated by a photoreduction of their FAD cofactor. In most photolyases, this proceeds electron transfer along chain three tryptophan (Trp) residues, connecting the flavin to protein surface. Much less studied, animal (6-4) photolyases (repairing pyrimidine-pyrimidone photoproducts) particularly interesting as they were recently shown have longer chain, counting four Trp residues. Using femtosecond polarized...

The competition between excited-state proton transfer (ESPT) and torsion plays a central role in the photophysics of fluorescent proteins green protein (GFP) family their chromophores. Here, it was investigated single GFP chromophore analogue bearing o-hydroxy p-diethylamino substituents, OHIM. light-induced dynamics OHIM studied by femtosecond transient absorption spectroscopy, at different pH. We found that is determined electron-donating character diethylamino group: torsional relaxation...

Because of growing applications in advanced fluorescence imaging, the mechanisms and dynamics photoinduced reactions reversibly photoswitchable fluorescent proteins are currently attracting much interest. We report first time-resolved study photoswitching Dreiklang, so far only protein to undergo reversible chromophore hydration. Using broadband femtosecond transient absorption spectroscopy, we show that reaction is triggered by an ultrafast deprotonation phenol group excited state 100 fs....

<italic>Bacillus subtilis</italic> tRNA methyltransferase TrmFO: photoinduced ultrafast tyrosine oxidation produces a still protonated tryptophanyl radical.

We present a new molecular shuttle, consisting of calixarene core attached to two different photoactive centers, DCM and DMABN. show that K(+) ion bound the DCM-grafted crown is translocated towards other site molecule upon photoexcitation, but not released bulk.

We present new femtosecond transient-absorption and picosecond fluorescence experiments performed on OBIP, the oxyblepharismin-binding protein believed to trigger photophobic response of ciliate Blepharisma japonicum. The formerly identified heterogeneity sample is confirmed rationalized in terms two independent populations, called rOBIP nrOBIP. population undergoes a fast photocycle restoring initial ground state less than 500 ps. Intermolecular electron transfer followed by recombination...

Photoinduced calcium release from the crown ether-linked merocyanine DCM-crown is reexamined by femtosecond transient absorption spectroscopy with sub-100 fs time resolution. Photodisruption of bond linking cation to nitrogen atom shared and chromophore found take place in 130 fs. Confirming our previous reports, photoinduced intraligand charge transfer observed picosecond regime but kinetics involving three-components (1 ps, 8 ps 77 ps), together a 56 stimulated-emission time-resolved red...

The present work aims at characterizing the photophysical behavior of a first biomimetic cyclodextrin model (CD-PYP1) photoactive site yellow protein (PYP). hydrophobic cavity in which chromophore self-includes, mimics its local environment within protein. photoinduced deprotonated CD-PYP1 (dp-CD-PYP1) has been probed by femtosecond transient-absorption spectroscopy and compared to those free (pCT−) wild-type PYP. excited-state deactivation dp-CD-PYP1 is found be non-exponential, with slower...

The photophysics of a ditopic receptor potassium ion consisting 1,3-alternate calix[4]biscrown with merocyanine dye (DCM) inserted into each crown is reported. Thanks to the large difference between binding affinity for one and two ions, can find relative total concentrations ligand at which 1:1 complex most predominant respect free 2:1 whose amounts are few percents. Investigation by femtosecond transient absorption spectroscopy provides evidence ultrafast movement through calix[4]arene...

Class II photolyases utilize for the photoreduction of their flavin cofactor (FAD) a completely different tryptophan triad than most other and cryptochromes. To counter sped-up back electron transfer, they evolved an unusually fast deprotonation distal tryptophanyl radical cation (WH˙+) that is produced after excitation flavin. We studied primary aspects oxidized FAD by ultrafast transient absorption spectroscopy, using class photolyase from Methanosarcina mazei. With time constant 9.2 ps,...

Femtosecond measurements of the transient dichroism and near-IR time-resolved spectra revealed ultrafast delocalization cationic state in poly(N-vinylcarbazole), leading to carrier photogeneration.

Thymidylate is a vital DNA precursor synthesized by thymidylate synthases. ThyX flavin-dependent synthase found in several human pathogens and absent humans, which makes it potential target for antimicrobial drugs. This enzyme methylates the 2'-deoxyuridine 5'-monophosphate (dUMP) to 2'-deoxythymidine (dTMP) using reduced flavin adenine dinucleotide (FADH-) as prosthetic group (6R)-N5,N10-methylene-5,6,7,8-tetrahydrofolate (CH2THF) methylene donor. Recently, was shown that ThyX-catalyzed...

Dreiklang is a reversibly photoswitchable fluorescent protein used as probe in advanced fluorescence imaging. It undergoes unique and still poorly understood photoswitching mechanism based on the reversible addition of water molecule to chromophore. We report first comprehensive study dynamics this reaction by transient absorption spectroscopy from 100 fs seconds original two point variants. The picture that emerges our work competition between nonproductive pathways. found had low quantum...