15 research outputs found
Synthesis and properties of small molecules designed to covalently capture native and oxidized forms of protein tyrosine phosphatase 1B (PTP1B)
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Protein tyrosine phosphatase 1B (PTP1B) is a validated target for the treatment of type 2 diabetes and obesity. The discovery of selective inhibitors with drug-like properties has proven to be challenging because there are [about]80 PTP family members that share a similar and positively charged active site. To overcome these challenges, we have pursued two novel approaches for the covalent inactivation of PTP1B. Exo-affinity labeling agents exploit covalent reactions with amino acids outside the enzyme active site to gain both affinity and selectivity. We prepared several affinity labeling agents using a 12-step convergent synthesis. Enzyme assays revealed that some of these agents are capable of inactivating the enzyme by covalent modification. In another project, we prepared a low molecular weight mimic of the oxidized form of PTP1B that is generated in cells, during insulin signaling events. Seeking molecules capable of covalent capture of oxidized PTP1B, we treated this chemical model with several carbon nucleophiles, such as 1,3-diketones and sulfone-stabilized carbon anions. These carbon nucleophiles readily reacted with the model compound, under mild conditions to give stable adducts. Inactivation experiments revealed that 1,3-diketones are capable of inactivating the oxidized PTP1B at micromolar concentrations
Therapeutic Targeting of Protein Tyrosine Phosphatases from Mycobacterium tuberculosis
Tuberculosis (TB) is an airborne infectious disease caused by Mycobacterium tuberculosis (Mtb). According to the World Health Organization, an estimated 10 million people developed TB in 2018. The occurrence of drug-resistant TB demands therapeutic agents with novel mechanisms of action. Antivirulence is an alternative strategy that targets bacterial virulence factors instead of central growth pathways to treat disease. Mycobacterium protein tyrosine phosphatases, mPTPA and mPTPB, are secreted by Mtb into the cytoplasm of macrophages and are required for survival and growth of infection within the host. Here we present recent advances in understanding the roles of mPTPA and mPTPB in the pathogenesis of TB. We also focus on potent, selective, and well-characterized small molecule inhibitors reported in the last decade for mPTPA and mPTPB
Crystal structure of 5-{4′-[(2-{2-[2-(2-ammonioethoxy)ethoxy]ethoxy}ethyl)carbamoyl]-4-methoxy-[1,1′-biphenyl]-3-yl}-3-oxo-1,2,5-thiadiazolidin-2-ide 1,1-dioxide: a potential inhibitor of the enzyme protein tyrosine phosphatase 1B (PTP1B)
The title compound, C24H32N4O8S, (I), crystallizes as a zwitterion. The terminal amine N atom of the [(2-{2-[2-(2-ammonioethoxy)ethoxy]ethoxy}ethyl)carbamoyl] side chain is protonated, while the 1,2,5-thiadiazolidin-3-one 1,1-dioxide N atom is deprotonated. The side chain is turned over on itself with an intramolecular N—H...O hydrogen bond. The 1,2,5-thiadiazolidin-3-one 1,1-dioxide ring has an envelope conformation with the aryl-substituted N atom as the flap. Its mean plane is inclined by 62.87 (8)° to the aryl ring to which it is attached, while the aryl rings of the biphenyl unit are inclined to one another by 20.81 (8)°. In the crystal, molecules are linked by N—H...O and N—H...N hydrogen bonds, forming slabs lying parallel to (010). Within the slabs there are C—H...O and C—H...N hydrogen bonds and C—H...π interactions present
Allylation and Alkylation of Biologically Relevant Nucleophiles by Diallyl Sulfides
Allyl
sulfides are bioactive phytochemicals found in garlic, onion,
and other members of the genus <i>Allium</i>. Here we showed
that diallyl disulfide and diallyl trisulfide can transfer allyl side
chains to low molecular weight thiols. Diallyl monosulfide is inert
with respect to this allyl transfer reaction. On the other hand, diallyl
sulfone, a known metabolite of diallyl monosulfide, alkylates both
amines and thiols under physiologically relevant conditions via isomerization
to an electrophilic vinyl sulfone
HighlyQ1: Please confirm the edits made to the article title are correct. Potent and Selective NAryl Oxamic Acid-Based Inhibitors for Mycobacterium tuberculosis Protein Tyrosine Phosphatase B
Reactions of 1,3-Diketones with a Dipeptide Isothiazolidin-3-one: Toward Agents That Covalently Capture Oxidized Protein Tyrosine Phosphatase 1B
Protein tyrosine phosphatase 1B (PTP1B)
is a validated therapeutic
target for the treatment of type 2 diabetes; however, the enzyme has
been classified by some as an “undruggable target”.
Here we describe studies directed toward the development of agents
that covalently capture the sulfenyl amide “oxoform”
of PTP1B generated during insulin signaling events. The sulfenyl amide
residue found in oxidized PTP1B presents a unique electrophilic sulfur
center that may be exploited in drug and probe design. Covalent capture
of oxidized PTP1B could permanently disable the intracellular pool
of enzyme involved in regulation of insulin signaling. Here, we employed
a dipeptide model of oxidized PTP1B to investigate the nucleophilic
capture of the sulfenyl amide residue by structurally diverse 1,3-diketones.
All of the 1,3-diketones examined here reacted readily with the electrophilic
sulfur center in the sulfenyl amide residue to generate stable covalent
attachments. Several different types of products were observed, depending
upon the substituents present on the 1,3-diketone. The results provide
a chemical foundation for the development of agents that covalently
capture the oxidized form of PTP1B generated in cells during insulin
signaling events
Rational design of reversible and irreversible cysteine sulfenic acid-targeted linear C-nucleophiles
Sulfone-stabilized carbanions for the reversible covalent capture of a posttranslationally-generated cysteine oxoform found in protein tyrosine phosphatase 1B (PTP1B)
Importance of the C‑Terminus of Aldehyde Dehydrogenase 7A1 for Oligomerization and Catalytic Activity
Aldehyde
dehydrogenase 7A1 (ALDH7A1) catalyzes the terminal step
of lysine catabolism, the NAD<sup>+</sup>-dependent oxidation of α-aminoadipate
semialdehyde to α-aminoadipate. Structures of ALDH7A1 reveal
the C-terminus is a gate that opens and closes in response to the
binding of α-aminoadipate. In the closed state, the C-terminus
of one protomer stabilizes the active site of the neighboring protomer
in the dimer-of-dimers tetramer. Specifically, Ala505 and Gln506 interact
with the conserved aldehyde anchor loop structure in the closed state.
The apparent involvement of these residues in catalysis is significant
because they are replaced by Pro505 and Lys506 in a genetic deletion
(c.1512delG) that causes pyridoxine-dependent epilepsy. Inspired by
the c.1512delG defect, we generated variant proteins harboring either
A505P, Q506K, or both mutations (A505P/Q506K). Additionally, a C-terminal
truncation mutant lacking the last eight residues was prepared. The
catalytic behaviors of the variants were examined in steady-state
kinetic assays, and their quaternary structures were examined by analytical
ultracentrifugation. The mutant enzymes exhibit a profound kinetic
defect characterized by markedly elevated Michaelis constants for
α-aminoadipate semialdehyde, suggesting that the mutated residues
are important for substrate binding. Furthermore, analyses of the
in-solution oligomeric states revealed that the mutant enzymes are
defective in tetramer formation. Overall, these results suggest that
the C-terminus of ALDH7A1 is crucial for the maintenance of both the
oligomeric state and the catalytic activity
Covalent Allosteric Inactivation of Protein Tyrosine Phosphatase 1B (PTP1B) by an Inhibitor–Electrophile Conjugate
Protein tyrosine
phosphatase 1B (PTP1B) is a validated drug target,
but it has proven difficult to develop medicinally useful, reversible
inhibitors of this enzyme. Here we explored covalent strategies for
the inactivation of PTP1B using a conjugate composed of an active
site-directed 5-aryl-1,2,5-thiadiazolidin-3-one 1,1-dioxide inhibitor
connected via a short linker to an electrophilic α-bromoacetamide
moiety. Inhibitor–electrophile conjugate <b>5a</b> caused
time-dependent loss of PTP1B activity consistent with a covalent inactivation
mechanism. The inactivation occurred with a second-order rate constant
of (1.7 ± 0.3) × 10<sup>2</sup> M<sup>–1</sup> min<sup>–1</sup>. Mass spectrometric analysis of the inactivated enzyme
indicated that the primary site of modification was C121, a residue
distant from the active site. Previous work provided evidence that
covalent modification of the allosteric residue C121 can cause inactivation
of PTP1B [Hansen, S. K., Cancilla, M. T., Shiau, T. P., Kung, J.,
Chen, T., and Erlanson, D. A. (2005) <i>Biochemistry</i> <i>44</i>, 7704–7712]. Overall, our results are
consistent with an unusual enzyme inactivation process in which noncovalent
binding of the inhibitor–electrophile conjugate to the active
site of PTP1B protects the nucleophilic catalytic C215 residue from
covalent modification, thus allowing inactivation of the enzyme via
selective modification of allosteric residue C121