158 research outputs found
Asteroseismology of the Hyades red giant and planet host epsilon Tauri
Asteroseismic analysis of solar-like stars allows us to determine physical
parameters such as stellar mass, with a higher precision compared to most other
methods. Even in a well-studied cluster such as the Hyades, the masses of the
red giant stars are not well known, and previous mass estimates are based on
model calculations (isochrones). The four known red giants in the Hyades are
assumed to be clump (core-helium-burning) stars based on their positions in
colour-magnitude diagrams, however asteroseismology offers an opportunity to
test this assumption. Using asteroseismic techniques combined with other
methods, we aim to derive physical parameters and the evolutionary stage for
the planet hosting star epsilon Tau, which is one of the four red giants
located in the Hyades. We analysed time-series data from both ground and space
to perform the asteroseismic analysis. By combining high signal-to-noise (S/N)
radial-velocity data from the ground-based SONG network with continuous
space-based data from the revised Kepler mission K2, we derive and characterize
27 individual oscillation modes for epsilon Tau, along with global oscillation
parameters such as the large frequency separation and the ratio between the
amplitude of the oscillations measured in radial velocity and intensity as a
function of frequency. The latter has been measured previously for only two
stars, the Sun and Procyon. Combining the seismic analysis with interferometric
and spectroscopic measurements, we derive physical parameters for epsilon Tau,
and discuss its evolutionary status.Comment: 13 pages, 13 figures, 4 tables, accepted for publication in Astronomy
& Astrophysic
Targeting undruggable carbohydrate recognition sites through focused fragment library design
Carbohydrate-protein interactions are key for cell-cell and host-pathogen recognition and
thus, emerged as viable therapeutic targets. However, their hydrophilic nature poses major
limitations to the conventional development of drug-like inhibitors. To address this shortcoming, four fragment libraries were screened to identify metal-binding pharmacophores
(MBPs) as novel scaffolds for inhibition of Ca2+-dependent carbohydrate-protein interactions. Here, we show the effect of MBPs on the clinically relevant lectins DC-SIGN, Langerin,
LecA and LecB. Detailed structural and biochemical investigations revealed the specificity of
MBPs for different Ca2+-dependent lectins. Exploring the structure-activity relationships of
several fragments uncovered the functional groups in the MBPs suitable for modification to
further improve lectin binding and selectivity. Selected inhibitors bound efficiently to DCSIGN-expressing cells. Altogether, the discovery of MBPs as a promising class of Ca2+-
dependent lectin inhibitors creates a foundation for fragment-based ligand design for future
drug discovery campaigns
- …