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The spontaneous emission of reaction centers from native and mutated Rhodobacter sphaeroides and from wild type Chloroflexus aurantiacus is investigated by fluorescence up-conversion with high temporal resolution. The time constant of 0.9 ps previously observed in transient absorption experiments on wild type reaction centers of Rhodobacter sphaeroides does(More)
X-ray crystallography and nuclear magnetic resonance measurements provide us with atomically resolved structures of an ever-growing number of biomolecules. These static structural snapshots are important to our understanding of biomolecular function, but real biomolecules are dynamic entities that often exploit conformational changes and transient molecular(More)
We have investigated the site-specific folding kinetics of a photoswitchable cross-linked alpha-helical peptide by using single (13)C = (18)O isotope labeling together with time-resolved IR spectroscopy. We observe that the folding times differ from site to site by a factor of eight at low temperatures (6 degrees C), whereas at high temperatures (45 degrees(More)
By covalently linking an azobenzene photoswitch across the binding groove of a PDZ domain, a conformational transition, similar to the one occurring upon ligand binding to the unmodified domain, can be initiated on a picosecond timescale by a laser pulse. The protein structures have been characterized in the two photoswitch states through NMR spectroscopy(More)
Stable subpicosecond infrared pulses in the spectral region of 4.5-11.5 microm are generated by difference-frequency mixing in AgGaS(2). The system uses femtosecond pulses from a Ti:sapphire regenerative amplifier and from a tunable traveling-wave dye laser. The infrared pulses have a duration of 400 fs, an energy of more than 10 nJ, and a repetition rate(More)
A series of photoswitchable, R-helical peptides were studied using two-dimensional infrared spectroscopy (2D-IR). Single-isotope labeling with 13 C 18 O at various positions in the sequence was employed to spectrally isolate particular backbone positions. We show that a single 13 C 18 O label can give rise to two bands along the diagonal of the 2D-IR(More)
Detailed studies of the subpicosecond kinetics in the primary electron transfer of reaction centers of Rhodopseudomonas viridis The primary, light-induced charge separation in reaction centers of Rhodopseudomonas widis is investigated with femtosecond time resolution. The absorption changes after direct excitation of the primary donor P at 955 nm are(More)
In a combined experimental-theoretical study, we investigated the transport of vibrational energy from the surrounding solvent into the interior of a heme protein, the sperm whale myoglobin double mutant L29W-S108L, and its dependence on temperature from 20 to 70 K. The hindered libration of a CO molecule that is not covalently bound to any part of the(More)
There is still an open debate regarding the structure forming capabilities of water at ambient conditions. To probe the presence of such inhomogeneities, we apply complex network analysis methods to a molecular dynamics simulation at room temperature. This study provides both a structural and quantitative characterization of kinetically homogeneous(More)