A5028662408- Chemical Synthesis and Analysis
- Click Chemistry and Applications
- Parkinson's Disease Mechanisms and Treatments
- RNA and protein synthesis mechanisms
- Peptidase Inhibition and Analysis
- Alzheimer's disease research and treatments
- Protein Structure and Dynamics
- DNA and Nucleic Acid Chemistry
- Electron Spin Resonance Studies
- Biotin and Related Studies
- Enzyme Structure and Function
- Biochemical and Molecular Research
- Monoclonal and Polyclonal Antibodies Research
- Neurological disorders and treatments
- Ubiquitin and proteasome pathways
- Supramolecular Self-Assembly in Materials
- Photosynthetic Processes and Mechanisms
- RNA modifications and cancer
- Cellular transport and secretion
- Botulinum Toxin and Related Neurological Disorders
- Advanced Fluorescence Microscopy Techniques
- Signaling Pathways in Disease
- Receptor Mechanisms and Signaling
- Mass Spectrometry Techniques and Applications
- Molecular Sensors and Ion Detection
University of Pennsylvania
2016-2025
California University of Pennsylvania
2014-2025
Philadelphia University
2014-2024
Cancer Research Institute
2019
Novem (Netherlands)
2018
Yale University
2006-2008
Division of Chemistry
2006
California Institute of Technology
2002-2004
Massachusetts Institute of Technology
2004
University of California, Los Angeles
2004
We recently reported that β-peptides can form discrete hetero-oligomers in aqueous solution. Here we describe the structure of such an oligomer as determined by X-ray crystallography. The Zwit-1F reveals a homo-octamer two cupped "hands" composed both parallel and antiparallel 314-helices. core assembly is entirely solvent-excluded β3-homoleucine residues. shares many physical characteristics natural proteins.
A mechanistically distinct, Ni/photoredox-catalyzed arylation of unprotected, native thiols (<italic>e.g.</italic>, cysteine residues) is reported – a process initiated through visible light-promoted, hydrogen atom transfer (HAT) event under ambient conditions.
Decreasing the size of spectroscopic probes can afford higher-resolution structural information from fluorescence experiments. Therefore, we have developed p-cyanophenylalanine (Cnf) and backbone thioamides as a fluorophore/quencher pair. Through examination series thiopeptides, determined working distance for this pair to be 8−30 Å. We also carried out proof-of-principle protein-folding experiment in which Cnf/thioamide-labeled version villin headpiece HP35 was thermally unfolded while...
The amino acid acridon-2-ylalanine (Acd) can be a valuable probe of protein conformational change because it is long lifetime, visible wavelength fluorophore that small enough to incorporated during ribosomal biosynthesis. Incorporation Acd into proteins expressed in Escherichia coli requires efficient chemical synthesis produce large quantities the and generation mutant aminoacyl tRNA synthetase selectively charge onto tRNA. Here, we report 87% yield over five steps from Tyr identification...
Small-molecule fluorescent probes are powerful tools for chemical biology; however, despite the large number of available, there is still a need simple fluorogenic scaffold, which allows rational design molecules with predictable photophysical properties and amenable to concise synthesis high-throughput screening. Here, we introduce highly modular quinoline-based probe containing three strategic domains that can be easily engineered optimized various applications. Such allotted (1) compound...
Peptide hormones are attractive as injectable therapeutics and imaging agents, but they often require extensive modification by mutagenesis and/or chemical synthesis to prevent rapid in vivo degradation. Alternatively, the single-atom, O-to-S of peptide backbone thioamidation has potential selectively perturb interactions with proteases while preserving other proteins, such target receptors. Here, we use validated diabetes therapeutic, glucagon-like peptide-1 (GLP-1), clinical investigation,...
Abstract Lewy bodies (LBs) are complex, intracellular inclusions that common pathological features of many neurodegenerative diseases. They consist largely aggregated forms the protein alpha-Synuclein (α-Syn), which misfolds to give rise beta-sheet rich amyloid fibrils. The aggregation monomers into fibrils occurs readily in vitro and pre-formed (PFFs) generated from recombinant α-Syn basis models LB These PFFs recapitulate phenotypes both cultured cells animal including formation rich,...
We have recently shown that p-cyanophenylalanine (Cnf) and a thioamide can be used as minimally perturbing Förster resonant energy transfer (FRET) pair to monitor protein conformation. also analogues of natural amino acids incorporated into full-sized proteins through native chemical ligation. For intermolecular studies with Cnf/thioamide FRET pairs, Cnf expressed in Escherichia coli unnatural acid mutagenesis using Cnf-specific tRNA synthetase. intramolecular studies, Cnf-labeled fragment...
Thioamide modifications of the peptide backbone are used to perturb secondary structure, inhibit proteolysis, as photoswitches, and spectroscopic labels. Thus far, their incorporation has been confined single peptides synthesized on solid phase. We have generated thioamides in C-terminal thioesters or N-terminal Cys fragments examined compatibility with native chemical ligation conditions. Most sequence variants can be coupled good yields either TCEP DTT reductant, though some byproducts...
Previously we have shown that thioamides can be incorporated into proteins as minimally perturbing fluorescence-quenching probes to study protein dynamics, folding, and aggregation. Here, show the spontaneity of photoinduced electron transfer between a thioamide an excited fluorophore is governed by redox potentials each moiety according Rehm–Weller-type model. We used this model predict quenching various common fluorophores, rigorously tested more than dozen examples. In case, found...
Fluorescent probe pairs that can be selectively excited in the presence of Trp and Tyr are great utility studying conformational changes proteins. However, size these restrict their incorporation to small portions a protein sequence where effects on secondary tertiary structure tolerated. Our findings show thioamide bond-a single atom substitution peptide backbone-can quench fluorophores red-shifted from intrinsic fluorescence, such as acridone. Using steady-state fluorescence lifetime...
Thioamides are single atom substitutions of the peptide bond that serve as versatile probes protein structure.
The fibrillary aggregation of the protein alpha synuclein (Asyn) is a hallmark Parkinson's disease, and identification small molecule binding sites on fibrils essential to development diagnostic imaging probes. A series molecular modeling, photoaffinity labeling, mass spectrometry, radioligand studies were conducted Asyn fibrils. results these revealed presence three different within fibrillar capable molecules with moderate high affinity. knowledge amino acid residues in will be important...
The binding of three distinct agonistsacetylcholine (ACh), nicotine, and epibatidineto the nicotinic acetylcholine receptor has been probed using unnatural amino acid mutagenesis. ACh makes a cation−π interaction with Trp α149, while nicotine employs hydrogen bond to backbone carbonyl in same region agonist site. analogue epibatidine achieves its high potency by taking advantage both bond. A simple structural model that considers only possible interactions α149 suggests novel aromatic...
To study conformational transitions at the muscle nicotinic acetylcholine (ACh) receptor (nAChR), a rhodamine fluorophore was tethered to Cys side chain introduced β19′ position in M2 region of nAChR expressed Xenopus oocytes. This procedure led only minor changes function. During agonist application, fluorescence increased by (Δ F / ) ≈10%, and emission peak shifted lower wavelengths, indicating more hydrophobic environment for fluorophore. The dose–response relations Δ agreed well with...
A 28 residue "retro" β-peptide has been designed to self-assemble as a tetramer, successfully recapitulating the octameric bundle complex Zwit-1F. Z28, largest synthesized date, was achieved in linear, microwave-assisted synthesis 19% isolated yield and high purity. Z28 forms expected tetrameric is more stable cooperative its folding than The successful design of an important step toward true β-amino acid proteins.