A5006267735- Advanced NMR Techniques and Applications
- Protein Structure and Dynamics
- Alzheimer's disease research and treatments
- NMR spectroscopy and applications
- Enzyme Structure and Function
- Supramolecular Self-Assembly in Materials
- Molecular spectroscopy and chirality
- Solid-state spectroscopy and crystallography
- Cancer-related Molecular Pathways
- Bacteriophages and microbial interactions
- Advanced MRI Techniques and Applications
- Muon and positron interactions and applications
- Microtubule and mitosis dynamics
- Quantum, superfluid, helium dynamics
- Peptidase Inhibition and Analysis
- Mechanisms of cancer metastasis
- Computational Drug Discovery Methods
- Alkaline Phosphatase Research Studies
- Metabolomics and Mass Spectrometry Studies
- Advanced biosensing and bioanalysis techniques
- Metal complexes synthesis and properties
- Electrochemical Analysis and Applications
- Dendrimers and Hyperbranched Polymers
- Monoclonal and Polyclonal Antibodies Research
- HER2/EGFR in Cancer Research
University of Puerto Rico System
2018-2024
University of Puerto Rico at Río Piedras
2018-2024
Clinical Research Puerto Rico
2018
National Institute of Diabetes and Digestive and Kidney Diseases
2013-2016
National Institutes of Health
2013-2016
Massachusetts Institute of Technology
2006-2013
University of Leeds
2010
ETH Zurich
2009
Rutgers, The State University of New Jersey
2003-2006
Joint Center for Structural Genomics
2006
The cross-β amyloid form of peptides and proteins represents an archetypal widely accessible structure consisting ordered arrays β-sheet filaments. These complex aggregates have remarkable chemical physical properties, the conversion normally soluble functional forms into structures is linked to many debilitating human diseases, including several common age-related dementia. Despite their importance, however, fibrils proved be recalcitrant detailed structural analysis. By combining...
The antibacterial peptide microcin J25 (MccJ25) inhibits bacterial transcription by binding within, and obstructing, the nucleotide-uptake channel of RNA polymerase. Published covalent three-dimensional structures indicate that MccJ25 is a 21-residue cycle. Here, we show published are incorrect, in fact "lariat protoknot", consisting an 8-residue cyclic segment followed 13-residue linear loops back threads through segment. first example lariat protoknot involving backbone-side chain amide linkage.
We describe magic-angle spinning NMR experiments designed to elucidate the interstrand architecture of amyloid fibrils. Three methods are introduced for this purpose, two being based on analysis long-range 13C–13C correlation spectra and third identification intermolecular interactions in 13C–15N spectra. show, studies fibrils formed by 86-residue SH3 domain PI3 kinase (PI3-SH3 or PI3K-SH3), that efficient display a resonance degeneracy establishes parallel, in-register alignment proteins In...
Quantitative solid-state NMR distance measurements in strongly coupled spin systems are often complicated due to the simultaneous presence of multiple noncommuting interactions. In case zeroth-order homonuclear dipolar recoupling experiments, recoupled interaction between distant spins is attenuated by stronger couplings nearby spins, an effect known as truncation. this article, we quantitatively investigate truncation on polarization-transfer efficiency various experiments with analytical...
Dynamic nuclear polarization (DNP) utilizes the inherently larger of electrons to enhance sensitivity conventional solid-state NMR experiments at low temperature. Recent advances in instrumentation development and sample preparation have transformed this field opened up new opportunities for its application biological systems. Here, we present DNP-enhanced 13C–13C 15N–13C correlation on GNNQQNY nanocrystals amyloid fibrils acquired 9.4 T 100 K demonstrate that DNP can be used obtain...
Protein magic angle spinning (MAS) NMR spectroscopy has generated structural models of several amyloid fibril systems, thus providing valuable information regarding the forces and interactions that confer extraordinary stability architecture. Despite these advances, however, obtaining atomic resolution describing higher levels organization within fibrils remains a significant challenge. Here, we detail MAS experiments sample labeling schemes designed specifically to probe such order...
Protein-protein interactions and the complexes thus formed are critical elements in a wide variety of cellular events that require an atomic-level description to understand them detail. Such typically constitute challenging systems characterize drive development innovative biophysical methods. NMR spectroscopy techniques can be applied extract atomic resolution information on binding interfaces, intermolecular affinity, binding-induced conformational changes protein-protein solution, cell...
β2-Microglobulin (β2m) is the major structural component of amyloid fibrils deposited in a condition known as dialysis-related amyloidosis. Despite numerous studies that have elucidated important aspects fibril formation process vitro, and magic angle spinning (MAS) NMR study formed by small peptide fragment, details β2m full-length 99-residue protein are largely unknown. Here, we present site-specific MAS analysis compare spectra prepared under two different conditions. Specifically, long...
We describe solid-state NMR homonuclear recoupling experiments at high magic-angle spinning (MAS) frequencies using the radio frequency-driven (RFDR) scheme. The effect of heteronuclear decoupling interference during RFDR is investigated experimentally and via numerical simulations, resulting in identification optimal conditions. effects MAS frequency, RF field amplitude, bandwidth, chemical shift offsets are examined. Most significantly, it shown that broadband correlation spectra can be...
The deposition of amyloid-like fibrils, composed primarily the 99-residue protein β2-microglobulin (β2m), is one characteristic symptoms dialysis-related amyloidosis. Fibrils formed in vitro at low pH and salt concentration share many properties with disease related fibrils have been extensively studied by a number biochemical biophysical methods. These contain significant β-sheet core complex cryoEM electron density profile. Here, we investigate intrasheet arrangement means 15N−13C MAS NMR...
The SH3 domain of the PI3 kinase (PI3-SH3 or PI3K-SH3) readily aggregates into fibrils in vitro and has served as an important model system investigation molecular properties mechanism formation amyloid fibrils. We describe conformation PI3-SH3 fibril form revealed by magic-angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) spectroscopy. MAS NMR spectra these display excellent resolution, with narrow 13C 15N line widths, representing a high degree structural order absence...
In this work, we explore the use of electrochemical methods (i.e., impedance) along with arsenic-specific aptamer (ArsSApt) to fabricate and study interfacial properties an arsenic (As(III)) sensor. The ArsSApt layer was self-assembled on a gold substrate, upon binding As(III), detectable change in impedimetric signal recorded because conformational changes at layer. These are linearly correlated concentration present system. This target-induced utilized for selective detection As(III)...
We present a new homonuclear recoupling sequence, CMAR, that allows observation of 2D 13C−13C correlation spectra at high magnetic fields and MAS frequencies (10−30 kHz). The main advantages the sequence are it provides efficient, broadband dipolar concurrently decouples 1H spins from 13C's. Thus, no additional decoupling is required during mixing period, thereby significantly reducing radio frequency power requirements for experiment. CMAR extends range applicability usual techniques should...
Maturation of HIV-1 requires disassembly the Gag polyprotein lattice, which lines viral membrane in immature state, and subsequent assembly mature capsid protein encloses RNA state. Metastability lattice has been proposed to depend on existence a structurally ordered, α-helical segment spanning junction between (CA) spacer peptide 1 (SP1) subunits Gag, that is dynamically disordered lattice. We report solid state nuclear magnetic resonance (ssNMR) measurements noncrystalline, spherical...
Gas vesicles are gas-filled buoyancy organelles with walls that consist almost exclusively of gas vesicle protein A (GvpA). Intact, collapsed from the cyanobacterium Anabaena flos-aquae were studied by solid-state NMR spectroscopy, and most GvpA sequence was assigned. Chemical shift analysis indicates a coil-α-β-β-α-coil peptide backbone, consistent secondary-structure-prediction algorithms, complementary information about mobility solvent exposure yields picture overall topology subunit is...
Highly efficient polarization transfer can be achieved in the magic-angle spinning NMR analysis of proteins by combination 13C labeling at alternating positions and band-selective radio-frequency-driven recoupling (BASE RFDR), a pulse scheme aimed exploiting bandwidth selectivity favorable effects weak radio-frequency irradiation to reintroduce homonuclear dipolar interactions between distant nuclei. Detailed facts importance specialist readers are published as "Supporting Information". Such...
Triple-negative breast cancer (TNBC) is an aggressive form of cancer, with a high predisposition for locally invasive and metastatic cancer. With the objective to reduce metastasis, we developed small molecule inhibitors target drivers Rho GTPases Rac Cdc42. Of these, MBQ-167 inhibits both Cdc42 IC50s 103 78 nmol/L, respectively; consequently, p21-activated kinase (PAK) signaling, cell proliferation, migration, mammosphere growth; induces cell-cycle arrest apoptosis; decreases HER2-type...
The HIV-1 capsid protein (CA) forms the shell that encloses RNA within a mature virion. Previous studies by electron microscopy have shown is primarily triangular lattice of CA hexamers, with variable curvature destroys ideal symmetry planar lattice. depends on dimerization, which occurs through interactions between helix 9 segments C-terminal domain (CTD) CA. Several high-resolution structures CTD-CTD dimerization interface been reported, based X-ray crystallography and multidimensional...
Scientists have established a connection between environmental exposure to toxins like β-