4 research outputs found
Efficient Synthesis of Protein Mimics by Sequential Native Chemical Ligation
Synthetic
mimics of protein surfaces have the potential to become
inhibitors of protein–protein interactions or even synthetic
vaccines. However, the synthesis of these complicated molecular constructs
is still difficult. Here we describe an efficient and versatile synthesis
of protein mimics containing up to three different cyclic peptides.
Using a sequential native chemical ligation strategy, peptide loops
containing a thioester handle were introduced onto a triazacyclophane
scaffold bearing orthogonal protected cysteine residues
Synthesis of Cyclic Peptides Containing a Thioester Handle for Native Chemical Ligation
The synthesis of cyclic peptides containing a thioester
handle
using a sulfo-click linker is reported. These cyclic peptides can
be coupled to N-terminal cysteine-containing constructs via native
chemical ligation. A successful application of a cyclic peptide bearing
a thioester handle in native chemical ligation is shown by a high
yielding ligation
Potent and Highly Selective Inhibitors of the Proteasome Trypsin-like Site by Incorporation of Basic Side Chain Containing Amino Acid Derived Sulfonyl Fluorides
A unique
category of basic side chain containing amino acid derived
sulfonyl fluorides (SFs) has been synthesized for incorporation into
new proteasome inhibitors targeting the trypsin-like site of the 20S
proteasome. Masking the former α-amino functionality of the
amino acid starting derivatives as an azido functionality allowed
an elegant conversion to the corresponding amino acid derived sulfonyl
fluorides. The inclusion of different SFs at the P<sub>1</sub> site
of a proteasome inhibitor resulted in 14 different peptidosulfonyl
fluorides (PSFs) having a high potency and an excellent selectivity
for the proteolytic activity of the β2 subunit over that of
the β5 subunit. The results of this study strongly indicate
that a free N-terminus of PSFs inhibitors is crucial for high selectivity
toward the trypsin-like site of the 20S proteasome. Nevertheless,
all compounds are slightly more selective for inhibition of the constitutive
over the immunoproteasome
Design, Synthesis, and Evaluation of a Diazirine Photoaffinity Probe for Ligand-Based Receptor Capture Targeting G Protein-Coupled Receptors.
Chemoproteomic approaches to identify ligand-receptor interactions have gained popularity. However, identifying transmembrane receptors remains challenging. A new trifunctional probe to aid the nonbiased identification of such receptors was developed and synthesized using a convenient seven-step synthesis. This probe contained three functional groups: 1) an N-hydroxysuccinimide ester for ligand-coupling through free amines, 2) a diazirine moiety to capture the receptor of interest upon irradiation with UV light, and 3) a biotin group which allowed affinity purification of the final adduct using streptavidin. The interaction between the G protein-coupled tachykinin neurokinin 1 (NK1) receptor, expressed in an inducible manner, and the peptidic ligand substance P was used as a test system. Liquid chromatography-mass spectrometry analysis confirmed successful coupling of the probe to substance P, while inositol monophosphate accumulation assays demonstrated that coupling of the probe did not interfere substantially with the substance P-NK1 receptor interaction. Confocal microscopy and western blotting provided evidence of the formation of a covalent bond between the probe and the NK1 receptor upon UV activation. As proof of concept, the probe was used in full ligand-based receptor-capture experiments to identify the substance P-binding receptor via liquid chromatography-tandem mass spectrometry, resulting in the successful identification of only the NK1 receptor. This provides proof of concept toward general utilization of this probe to define interactions between ligands and previously unidentified plasma-membrane receptors