49 research outputs found
Confined Dynamics of a Ribosome-Bound Nascent Globin: Cone Angle Analysis of Fluorescence Depolarization Decays in the Presence of Two Local Motions
The dependence of the molecular first hyperpolarizabilities of merocyanines on ground-state polarization and length
We report here the dipole moment (µ) and first hyperpolarizability (β) determined by electric field-induced second harmonic generation, for several merocyanine dyes containing an 1,3,3-trimethylindoline heterocycle as a ‘donor’ in which the ‘acceptor’ end of the molecule and the polyene bridge length was systematically varied; dyes with hexamethine bridges gave positive β, while that with a dimethine bridge gave a negative β value
Response of Rubredoxin from Pyrococcus furiosus to Environmental Changes: Implications for the Origin of Hyperthermostability
The bases of the hyperthermostability of rubredoxin from Pyrococcus furiosus (RdPf) have been probed by structural perturbations induced by solution pH and ionic strength changes. Comparison of the solution behavior at pH 7 and pH 2, as probed by far- and near-UV circular dichroism, Trp
fluorescence emission, l-anilinonaphthalene-8-sulfonate (ANS) binding, and NMR spectroscopy, reveals the presence of only minimal structural variations at room temperature. At pH 2, the protein displays a surprising nearly native-like behavior at high ionic strength while, at low ionic strength, it is capable of strongly binding the hydrophobic probe ANS. All the secondary and tertiary structural features, including the environment of the hydrophobic core, appear to be intact regardless of pH and ionic strength. The apparent "melting" or denaturation temperature at pH 2, however, is 42 °C lower than at pH 7. This is attributed to the perturbation of many electrostatic interactions, including the disruption of all the ion pairs, which is complete at pH 2, as indicated by electrometric pH titrations. The implications of these
findings for the origins of the hyperthermostability of rubredoxin are discussed
Response of Rubredoxin from Pyrococcus furiosus to Environmental Changes: Implications for the Origin of Hyperthermostability
The bases of the hyperthermostability of rubredoxin from Pyrococcus furiosus (RdPf) have been probed by structural perturbations induced by solution pH and ionic strength changes. Comparison of the solution behavior at pH 7 and pH 2, as probed by far- and near-UV circular dichroism, Trp
fluorescence emission, l-anilinonaphthalene-8-sulfonate (ANS) binding, and NMR spectroscopy, reveals the presence of only minimal structural variations at room temperature. At pH 2, the protein displays a surprising nearly native-like behavior at high ionic strength while, at low ionic strength, it is capable of strongly binding the hydrophobic probe ANS. All the secondary and tertiary structural features, including the environment of the hydrophobic core, appear to be intact regardless of pH and ionic strength. The apparent "melting" or denaturation temperature at pH 2, however, is 42 °C lower than at pH 7. This is attributed to the perturbation of many electrostatic interactions, including the disruption of all the ion pairs, which is complete at pH 2, as indicated by electrometric pH titrations. The implications of these
findings for the origins of the hyperthermostability of rubredoxin are discussed
Recommended from our members
Structure-activity studies of delta-selective opioid analogues
The two structurally different peptides DPDPE and Dermenkephalin show a similar remarkably high affinity and selectivity for the delta opioid receptor subtype. An effort has been made to gain some insight into the factors responsible for the recognition ability of these two molecules by synthesizing some DPDPE-Dermenkephalin peptide hybrids and some conformationally restricted Dermenkephalin analogues. The results of the binding and the in-vitro bioassays have been compared with those of the parent peptides. A general decrease in receptor affinity has been observed in the peptide hybrids while the dermenkephalin analogues have shown a wider range of affinities and selectivities. The above findings contribute to the understanding of the structural requirements of the delta receptor, provide information about the sensitivity of Dermenkephalin to enzymatic degradation, and indicate directions for future research
Confined Dynamics of a Ribosome-Bound Nascent Globin: Cone Angle Analysis of Fluorescence Depolarization Decays in the Presence of Two Local Motions
The Burial of Solvent-Accessible Surface Area is a Predictor of Polypeptide Folding and Misfolding as a Function of Chain Elongation
Fluorescein: A Photo-CIDNP Sensitizer Enabling Hypersensitive NMR Data Collection in Liquids at Low Micromolar Concentration
Photochemically induced dynamic nuclear
polarization (photo-CIDNP)
is a powerful approach for sensitivity enhancement in NMR spectroscopy.
In liquids, intermolecular photo-CIDNP depends on the transient bimolecular
reaction between photoexcited dye and sample of interest. Hence the
extent of polarization is sample-concentration dependent. This study
introduces fluorescein (FL) as a photo-CIDNP dye whose performance
is exquisitely tailored to data collection at extremely low sample
concentrations. The photo-CIDNP resonance intensities of tryptophan
in the presence of either FL or FMN (i.e., the routinely employed
flavin mononucleotide photosensitizer) in the liquid state show that
FL yields superior sensitivity and enables rapid data collection down
to an unprecedented 1 μM concentration. This result was achieved
on a conventional spectrometer operating at 14.1 T and equipped with
a room-temperature probe (i.e., noncryogenic). Kinetic simulations
show that the excellent behavior of FL arises from its long excited-state
triplet lifetime and superior photostability relative to conventional
photo-CIDNP sensitizers