Get Beam time
BioCAT is a national user facility funded by the NIH,
and beam time is free for experimenters. Beam time is awarded
through the APS GUP process, which considers feasibility
and scientific merit.
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Proteins May Prevent Dysfunction and Disease by Relaxing
A new study suggests many proteins remain expanded in the cell,
rather than contracting into tight folded shapes.
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Proteins May Prevent Dysfunction and Disease by Relaxing
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Unearthing the Mechanism of the Frank-Starling Law
Recent X-ray diffraction experiments show that the protein
titin is critically important for transmitting the stretch-induced
signals within the heart’s muscles known to impact the strength with
which the heart contracts. This work not only solves a piece of the
mystery of how the frank-Starling law determines cardiac function, but
provides an avenue for targeted development of drugs to treat heart failure.
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Unearthing the Mechanism of the Frank-Starling Law
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Titin-Based Force Modulates Cardiac Thick and Thin Filaments
The Frank-Starling Law of the Heart states that the heart’s
stroke volume increases with greater preload due to increased
venous return, allowing the heart to adapt to varying
circulatory demands. At the molecular level, increasing
preload increases sarcomere length (SL), which alters
structures w ithin the sarcomere that are correlated to
increased calcium sensitivity upon activation. The titin
protein, spanning the half-sarcomere acts as a spring in the
I-band, applies a SL-dependent passive force on the myosin
containing thick filaments changing its structure and
functional properties. Altered titin-based forces play a
crucial role in the etiology of many cardiomyopathies;
however, the disease state obscures titin’s role, impeding
therapeutic solutions. The authors studied titin’s specific
role and concluded that reducing titin-based forces blunts
structural changes in both thick and thin filaments while
leaving the length-dependent OFF-to-ON transition mechanism
intact, indicating a clear role for titin in the
Frank-Starling mechanism.
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How hydrophobicity, side chains, and salt affect the dimensions of disordered proteins
Understanding the driving forces behind stability of
denatured state ensembles (DSE’s) and intrinsically disordered
proteins (IDP’s) is central to a number of unresolved questions
in bimolecular thermodynamics regarding protein folding pathways
and foldability, thermodynamic stability, aggregation and
misfolding. Researchers at the University of Chicago and Notre
Dame used temperature-controlled size-exclusion
chromatography-coupled SAXS (SEC-SAXS) and NMR to examine how
temperature and solvent ionic strength influences the solution
structure(s) of the N-terminal domain of pertactin (PNt). PNt
is a valuable model system from a fundamental biophysical
point of view, as the full-length 539-residue pertactin folds
into a parallel β-helix but the 334 N-terminal residues do not
and instead behave as a highly expanded, intrinsically
disordered chain.
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Myosin-binding protein C regulates the sarcomere lattice and stabilizes the OFF states of myosin heads
Muscle contraction is produced via the interaction of
myofilaments and is regulated so that muscle performance
matches demand. Myosin-binding protein C (MyBP-C) is a long
and flexible protein that is thought to control muscle
contraction via the regulation of myosin motors, as mutations
lead to debilitating disease. Here the authors used combination
of mechanics and small-angle X-ray diffraction to study the
effects of immediate and selective removal of the particular
domains of fast MyBP-C on sarcomere structure and function in
permeabilized skeletal muscle. They concluded that the MyBP-C
domains play an important role in contractile performance.
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BioCAT Plans for the APS-U Dark Period
The APS shut down on April 17, 2023 for a major year-long
upgrade, the “APS-U” project. There is no user access to the
APS during this “dark period”. We anticipate that BioCAT will
resume user experiments in late 2024/early 2025. We continue
to help support experiments by our users at other beamlines,
including sending BioCAT staff to other beamlines to help with
some of the more complicated experiments, until operations
resume at BioCAT.
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Apply for Everything BioSAXS 10 Workshop
BioCAT is offering its tenth intensive HOW-TO course in BioSAXS.
Students will have four days of virtual lectures and hands-on
software tutorials on the basics of BioSAXS data collection and
processing from expert practitioners in the field. Students may
also be able to mail in samples for data collection on the BioCAT
beamline (Sector 18 at the APS) before the course, and there will
be time during the workshop to get help with analysis of their own
data. The course will take place from 12/10/24 to 12/13/24
and is entirely virtual (via Zoom).
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BioCAT awarded $2 million in supplementary funds to upgrade beamline
The BioCAT team has been awarded $2 million in
supplementary funds from the NIH to upgrade the BioCAT
beamline. These funds will let us upgrade our x-ray optics (mostly original to
the beamline and more than 20 years old) to modern state-of-the-art
systems that can take full advantage of the new upgraded APS source.
These new optics will provide smaller, more intense x-ray beams
and improved beam stability. The upgrade is expected to take ~2 years
to complete and user operations will continue unhindered while it is taking place.
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