24 research outputs found
Substrate-guided optimization of the syringolins yields potent proteasome inhibitors with activity against leukemia cell lines
Natural products that inhibit the proteasome have been fruitful starting points for the development of drug candidates. Those of the syringolin family have been underexploited in this context. Using the published model for substrate mimicry by the syringolins and knowledge about the substrate preferences of the proteolytic subunits of the human proteasome, we have designed, synthesized, and evaluated syringolin analogs. As some of our analogs inhibit the activity of the proteasome with second-order rate constants 5-fold greater than that of the methyl ester of syringolin B, we conclude that the substrate mimicry model for the syringolins is valid. The improvements in in vitro potency and the activities of particular analogs against leukemia cell lines are strong bases for further development of the syringolins as anti-cancer drugs.National Institutes of Health (U.S.) (Grant AI-16892
Rational Design of Selective and Bioactive Inhibitors of the Mycobacterium Tuberculosis Proteasome
The 20S core particle of the proteasome in Mycobacterium tuberculosis (Mtb) is a promising, yet unconventional, drug target. This multimeric peptidase is not essential, yet degrades proteins that have become damaged and toxic via reactions with nitric oxide (and/or the associated reactive nitrogen intermediates) produced during the host immune response. Proteasome inhibitors could render Mtb susceptible to the immune system, but they would only be therapeutically viable if they do not inhibit the essential 20S counterpart in humans. Selective inhibitors of the Mtb 20S were designed and synthesized on the bases of both its unique substrate preferences and the structures of substrate-mimicking covalent inhibitors of eukaryotic proteasomes called syringolins. Unlike the parent syringolins, the designed analogues weakly inhibit the human 20S (Hs 20S) proteasome and preferentially inhibit Mtb 20S over the human counterpart by as much as 74-fold. Moreover, they can penetrate the mycobacterial cell envelope and render Mtb susceptible to nitric oxide-mediated stress. Importantly, they do not inhibit the growth of human cell lines in vitro and thus may be starting points for tuberculosis drug development.National Institutes of Health (U.S.) (Grant AI-16892
Macrocyclization of Unprotected Peptide Isocyanates
A chemistry
for the facile two-component macrocyclization of unprotected
peptide isocyanates is described. Starting from peptides containing
two glutamic acid γ-hydrazide residues, isocyanates can be readily
accessed and cyclized with hydrazides of dicarboxylic acids. The choice
of a nucleophilic linker allows for the facile modulation of biochemical
properties of a macrocyclic peptide. Four cyclic NYAD-1 analogues
were synthesized using the described method and displayed a range
of biological activities
Efficient and Regiospecific Syntheses of Peptides with Piperazic and Dehydropiperazic Acids via a Multicomponent Reaction
Peptides containing
N2-acyl piperazic or 1,6-dehydropiperazic
acids can be formed efficiently via a novel multicomponent reaction
of 1,4,5,6-tetrahydropyridazines, isocyanides, and carboxylic
acids. Remarkably, the reaction’s induced intramolecularity
can enable the regiospecific formation of products with N2-acyl piperazic
acid, which counters the intrinsic and troublesome propensity for
piperazic acids to react at N1 in acylations. The utility of the methodology
is demonstrated in the synthesis of the bicyclic core of the interleukin-1β
converting enzyme inhibitor, Pralnacasan
Systematic Investigation of EDC/sNHS-Mediated Bioconjugation Reactions for Carboxylated Peptide Substrates
1-Ethyl-3-(3-(dimethylamino)propyl)carbodiimide
(EDC) bioconjugations
have been utilized in preparing variants for medical research. While
there have been advances in optimizing the reaction for aqueous applications,
there has been limited focus toward identifying conditions and side
reactions that interfere with product formation. We present a systematic
investigation of EDC/<i>N</i>-hydroxysulfosuccinimide (sNHS)-mediated
bioconjugations on carboxylated peptides and small proteins. We identified
yet-to-be-reported side products arising from both the reagents and
substrates. Model peptides used in this study illustrate particular
substrates are more susceptible to side reactions than others. From
our studies, we found that bioconjugations are more efficient with
high concentrations of amine nucleophile but not sNHS. Performing
bioconjugations on a model affibody protein show that the trends established
with model peptides hold for more complex systems
Systematic Investigation of EDC/sNHS-Mediated Bioconjugation Reactions for Carboxylated Peptide Substrates
Automated Fast-Flow Synthesis of Antisense Phosphorodiamidate Morpholino Oligomers
The
antisense phosphorodiamidate morpholino oligomer (PMO) drugs Eteplirsen and Golodirsen
are improving the lives of some Duchenne muscular dystrophy (DMD) patients, but
treating all DMD subtypes would require the development of over 50 novel
antisense therapies. To rapidly prototype personalized PMO for diseases such as
DMD, we designed a fully automated flow-based oligonucleotide synthesizer. Our
optimized high temperature synthesis platform reduces coupling times by up to
22-fold compared to previously reported batch methods. We demonstrate the power
of our new automated technology with the synthesis of milligram quantities of
an 18-mer reporter PMO sequence in 3.5 hours, three new potential therapeutic
PMO sequences targeted to exon 46 of the dystrophin gene in a single day, and a
candidate antiviral PMO sequence targeted to the SARS-CoV-2 genomic mRNA in 3.5
hours. This flexible flow synthesis platform can be used for on-demand
production of a broad range of personalized therapeutic polymers.</p
Fully automated fast-flow synthesis of antisense phosphorodiamidate morpholino oligomers
Rapid development of antisense therapies can enable on-demand responses to new viral pathogens and make personalized medicine for genetic diseases practical. Antisense phosphorodiamidate morpholino oligomers (PMOs) are promising candidates to fill such a role, but their challenging synthesis limits their widespread application. To rapidly prototype potential PMO drug candidates, we report a fully automated flow-based oligonucleotide synthesizer. Our optimized synthesis platform reduces coupling times by up to 22-fold compared to previously reported methods. We demonstrate the power of our automated technology with the synthesis of milligram quantities of three candidate therapeutic PMO sequences for an unserved class of Duchenne muscular dystrophy (DMD). To further test our platform, we synthesize a PMO that targets the genomic mRNA of SARS-CoV-2 and demonstrate its antiviral effects. This platform could find broad application not only in designing new SARS-CoV-2 and DMD antisense therapeutics, but also for rapid development of PMO candidates to treat new and emerging diseases
Substrate-guided optimization of the syringolins yields potent proteasome inhibitors with activity against leukemia cell lines
Natural products that inhibit the proteasome have been fruitful starting points for the development of drug candidates. Those of the syringolin family have been underexploited in this context. Using the published model for substrate mimicry by the syringolins and knowledge about the substrate preferences of the proteolytic subunits of the human proteasome, we have designed, synthesized, and evaluated syringolin analogs. As some of our analogs inhibit the activity of the proteasome with second-order rate constants 5-fold greater than that of the methyl ester of syringolin B, we conclude that the substrate mimicry model for the syringolins is valid. The improvements in in vitro potency and the activities of particular analogs against leukemia cell lines are strong bases for further development of the syringolins as anti-cancer drugs.National Institutes of Health (U.S.) (Grant AI-16892