The photoinduced electrocyclic ring-opening of a fluorinated indolylfulgide is investigated by stationary and ultrafast spectroscopy in the UV/vis spectral range. Photoreactions, initiated by optical excitation into the S1 (570 nm) and SN (340 nm) absorption band of the closed isomer, lead to considerable differences in reaction dynamics and quantum yields. ... READ MORE

DNA photolyases and cryptochromes (cry) form a family of flavoproteins that use light energy in the blue/UV-A region for the repair of UV-induced DNA lesions or for signaling, respectively. Very recently, it was shown that members of the DASH cryptochrome subclade repair specifically cyclobutane pyrimidine dimers (CPDs) in UV-damaged single-stranded DNA. Here, we ... READ MORE

Before and after: Crystal structures of the DNA (6-4) photolyase from D. melanogaster—one structure in complex with DNA containing a (6-4) lesion (see picture) and one in which the lesion has been repaired—provide new insight into lesion recognition and repair. The proposed mechanism for light-induced, electron-transfer-based repair of the (6-4) lesion does ... READ MORE

With the evolution of multidrug resistant bacterial pathogens, infectious diseases pose once again a serious threat to public health. Especially the opportunistic pathogen Staphylococcus aureus has gained importance through the dramatically increasing appearance of methicillin-resistant (MRSA) strains in hospitals and the recent emergence of epidemic ... READ MORE

Chaperone sind Proteine, die anderen Proteinen helfen, korrekt zu falten. Bislang ist allerdings noch nicht vollstaendig verstanden, inwiefern Chaperone aktiv in den Faltungszyklus eingreifen oder ob sie die noch ungefalteten Proteine nur passiv vor Fehlfaltungen und Aggregatbildung schuetzen. Unsere Ergebnisse zeigen, dass das Chaperonin GroEL aktiv in den ... READ MORE

With the development of antibiotic-resistant bacterial strains, infectious diseases have become again a life-threatening problem. One of the reasons for this dilemma is the limited number and breadth of current therapeutic targets for which several resistance strategies have evolved over time. To expand the number of addressable enzyme targets and to understand ... READ MORE

The spore photoproduct is a unique photolesion, formed in spores upon irradiation with UV light; to investigate the properties of spore photoproduct containing DNA we have synthesized 5S and 5R lesion analogs and incorporated them into DNA. ... READ MORE

Folding intermediates play a key role in defining protein folding and assembly pathways as well as those of misfolding and aggregation. Yet, due to their transient nature, they are poorly accessible to high-resolution techniques. Here, we made use of the intrinsically slow folding reaction of an antibody domain to characterize its major folding intermediate in ... READ MORE

The attachment of labels onto DNA is of utmost importance in many areas of biomedical research and is valuable in the construction of DNA-based functional nanomaterials. The copper(I)-catalyzed Huisgen cycloaddition of azides and alkynes (CuAAC) has recently been added to the repertoire of DNA labeling methods, thus allowing the virtuallyunlimited functionalization ... READ MORE

Evolution of multiresistant bacterial strains has meant that infectious diseases once again pose a major threat to public health. Since many antibiotics still target only a limited set of cellular functions, it is a desirable goal to expand the number and breadth of therapeutic targets as well as to gain a deeper understanding of the molecular mechanisms ... READ MORE

The ring-opening and ring-closure reactions of a photochromic indolylfulgimide are investigated with femtosecond vibrational spectroscopy. Spectral signatures due to excited-state decay and vibrational cooling are seen in the mid-IR region. For the ring-opening reaction triggered with visible pulses, a lifetime of the excited electronic state of 4 ps was obtained ... READ MORE

The GroEL/GroES chaperonin system mediates protein folding in the bacterial cytosol. Newly synthesized proteins reach GroEL via transfer from upstream chaperones such as DnaK/DnaJ (Hsp70).Herewe employedsinglemoleculeandensembleFRETtomonitor the conformational transitions of amodel substrate as it proceeds along this chaperone pathway. We find that DnaK/DnaJ ... READ MORE

The ultrafast ring-opening reaction of the molecular switch 1,2-Dimethyl-3-indolylfulgide dissolved in acetonitrile is investigated by temperature dependent quantum efficiency measurements and time-resolved transient absorption spectroscopy in the ultraviolet and visible spectral range. The photoreaction is found to be thermally activated with an activation energy ... READ MORE

Hemithioindigo-molecules show a photochromic behavior due to a photo-induced Z/E-isomerization on a picosecond timescale. Changes in the reaction kinetics, caused by polar substituents attached to the thioindigo-moiety, are studied using time-resolved absorption spectroscopy. The experiments reveal that substituents in the thioindigo-part influence the reaction ... READ MORE

The reaction dynamics of the complete photo cycle, ring-opening (C→E) and ring-closure (E→C), of N-methyl-(6-bromo-1,2-dimethyl-3-indolyl) fulgimide dissolved in acetonitrile are analysed via steady-state and ultrafast spectroscopy using transient absorption in the UV/VIS and mid-IR complemented by ultrafast fluorescence broad-band spectroscopy with a ... READ MORE

Single dye molecules incorporated into a mesoporous matrix can act as highly sensitive reporters of their environment. Here, we use single TDI molecules incorporated as guests into hexagonal mesoporous films containing highly structured domains. The dye molecules allow us to map the size of these domains which can extend to over 100 m. Investigation of the ... READ MORE

The oxidative DNA lesion, FaPydG rapidly anomerizes to form a mixture of the a and b anomer. To investigate the mutagenic potential of both forms, we prepared stabilized bioisosteric analogues of both configurational isomers and incorporated them into oligonucleotides. These were subsequently used for thermodynamic melting-point studies and for primerextension ... READ MORE

One, two, or three: An efficient, modular, and robust protocol has been developed for the multiple functionalization of DNA. It is based on the click reaction of azides with the alkyne substituents on an oligodeoxyribonucleotide (ODN), which was prepared by the standard phosphoramidite method (see scheme). ODNs can thus be labeled with two sensitive molecules, and ... READ MORE

After the complete sequencing of the human genome, one of the next important steps is to decipher the genetic mechanisms which allow cells to switch genes on and off. These processes are fundamental for cellular development. At the chemical level, gene silencing requires the selective methylation of of the C5-position of cytidines in DNA, and this established ... READ MORE

Die gepulste alternierende Anregung (pulsed interleaved excitation oder PIE) ist eine neue Methode, die es ermöglicht, mehr Informationen auseiner einzelnen Fluoreszenzmessung zu gewinnen. Pulsed interleaved excitation (PIE) is a new method for extending thecapabilities of fluorescence emission measurements. ... READ MORE