Innocent defendants sometimes plead guilty. This is a problem. Some suggest fixing this problem with a constitutional requirement that prosecutors disclose exculpatory evidence before a defendant ...pleads guilty. A circuit split has thus developed concerning whether Brady, which requires disclosure of exculpatory evidence, extends to the pre-plea context. The Supreme Court's jurisprudence, however, likely bars a constitutional requirement for pre-plea disclosure of exculpatory evidence. Faced with this exigency, this Comment argues that contract law should form the legal basis for pre-plea disclosure. Specifically, the contract doctrine of constructive fraud provides a suitable remedy. While big boy clauses, which defeat constructive fraud claims, initially appear disastrous to this regime, such clauses are likely the redeeming quality of a constructive fraud solution. To safeguard innocent defendants from using big boy clauses, this Comment suggests open bargaining and modifications to judicial plea colloquies.
Direct-acting antivirals are needed to combat coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The papain-like protease (PLpro) ...domain of Nsp3 from SARS-CoV-2 is essential for viral replication. In addition, PLpro dysregulates the host immune response by cleaving ubiquitin and interferon-stimulated gene 15 protein from host proteins. As a result, PLpro is a promising target for inhibition by small-molecule therapeutics. Here we design a series of covalent inhibitors by introducing a peptidomimetic linker and reactive electrophile onto analogs of the noncovalent PLpro inhibitor GRL0617. The most potent compound inhibits PLpro with k
/K
= 9,600 M
s
, achieves sub-μM EC
values against three SARS-CoV-2 variants in mammalian cell lines, and does not inhibit a panel of human deubiquitinases (DUBs) at >30 μM concentrations of inhibitor. An X-ray co-crystal structure of the compound bound to PLpro validates our design strategy and establishes the molecular basis for covalent inhibition and selectivity against structurally similar human DUBs. These findings present an opportunity for further development of covalent PLpro inhibitors.
Customization of deuterated biomolecules is vital for many advanced biological experiments including neutron scattering. However, because it is challenging to control the proportion and ...regiospecificity of deuterium incorporation in live systems, often only two or three synthetic lipids are mixed together to form simplistic model membranes. This limits the applicability and biological accuracy of the results generated with these synthetic membranes. Despite some limited prior examination of deuterating Escherichia coli lipids in vivo, this approach has not been widely implemented. Here, an extensive mass spectrometry-based profiling of E. coli phospholipid deuteration states with several different growth media was performed, and a computational method to describe deuterium distributions with a one-number summary is introduced. The deuteration states of 36 lipid species were quantitatively profiled in 15 different growth conditions, and tandem mass spectrometry was used to reveal deuterium localization. Regressions were employed to enable the prediction of lipid deuteration for untested conditions. Small-angle neutron scattering was performed on select deuterated lipid samples, which validated the deuteration states calculated from the mass spectral data. Based on these experiments, guidelines for the design of specifically deuterated phospholipids are described. This unlocks even greater capabilities from neutron-based techniques, enabling experiments that were formerly impossible.
Although metal-free cycloadditions of cyclooctynes and azides to give stable 1,2,3-triazoles have found wide utility in chemical biology and material sciences, there is an urgent need for faster and ...more versatile bioorthogonal reactions. We have found that nitrile oxides and diazocarbonyl derivatives undergo facile 1,3-dipolar cycloadditions with cyclooctynes. Cycloadditions with diazocarbonyl derivatives exhibited similar kinetics as compared to azides, whereas the reaction rates of cycloadditions with nitrile oxides were much faster. Nitrile oxides could conveniently be prepared by direct oxidation of the corresponding oximes with BAIB, and these conditions made it possible to perform oxime formation, oxidation, and cycloaddition as a one-pot procedure. The methodology was employed to functionalize the anomeric center of carbohydrates with various tags. Furthermore, oximes and azides provide an orthogonal pair of functional groups for sequential metal-free click reactions, and this feature makes it possible to multifunctionalize biomolecules and materials by a simple synthetic procedure that does not require toxic metal catalysts.
The reactivity of free NO (NO(+), NO(•), and NO(-)) with thiols (RSH) is relatively well understood, and the oxidation state of the NO moiety generally determines the outcome of the reaction. ...However, NO/RSH interactions are often mediated at metal centers, and the fate of these species when bound to a first-row transition metal (e.g., Fe, Co) deserves further investigation. Some metal-bound NO moieties (particularly NO(+), yielding S-nitrosothiols) have been more thoroughly studied, yet the fate of these species remains highly condition-dependent and, for M-NO(-), an unexplored field. Herein, we present an overview of thiol reactions with metal nitrosyls that result in N-O bond activation, ligand substitution on {MNO} fragments, and/or redox chemistry. We also present our results pertaining to the thiol reactivity of nonheme {FeNO}(7/8) complexes Fe(LN4(pr))(NO)(-/0) (1 and 2) and the noncorrin {CoNO}(8) complex Co(LN4(pr))(NO) (3), an isoelectronic analogue of the {FeNO}(8) complex 1. Among other products, the reaction of 1 with p-ClPhSH affords Fe2(μ-SPh-p-Cl)2(NO)4(-) (anion of 6), a reduced Roussin's red ester (rRRE), which was characterized by Fourier transform infrared (FTIR), UV-vis, electron paramagnetic resonance (EPR), and X-ray diffraction. Similarly, the reaction of 1 with glutathione in buffer affords the corresponding rRRE, which has also been spectroscopically characterized by EPR and UV-vis. The oxidation states of the metals and nitrosyls both contribute to the complex nature of these interactions, and as such, we discuss the varying product distribution accordingly. These studies shed insight into the products that may form through MNO/RSH interactions that lead to NOx activation and {MNO} redox.
The selective reduction of nitrite (NO2 –) to nitric oxide (NO) is a fundamentally important chemical transformation related to environmental remediation of NO x and mammalian blood flow. We report ...the synthesis and characterization of two nonheme Fe complexes, Fe(LN4 Im)(MeCN)2(BF4)2 (1 MeCN ) and Fe(LN4 Im)(NO2)2 (2), geared toward understanding the NO2 – to NO conversion. Complex 2 represents the first structurally characterized FeII complex with two axial NO2 – ligands that functions as a nitrite reduction catalyst.
Hole Hopping through Cytochrome P450 Sørensen, Mette L. H; Sanders, Brian C; Hicks, L. Perry ...
The journal of physical chemistry. B,
04/2020, Volume:
124, Issue:
15
Journal Article
Peer reviewed
Open access
High-potential iron–oxo species are intermediates in the catalytic cycles of oxygenase enzymes. They can cause heme degradation and irreversible oxidation of nearby amino acids. We have proposed that ...there are protective mechanisms in which hole hopping from oxidized hemes through tryptophan/tyrosine chains generates a surface-exposed amino-acid oxidant that could be rapidly disarmed by reaction with cellular reductants. In investigations of cytochrome P450 BM3, we identified Trp96 as a critical residue that could play such a protective role. This Trp is cation−π paired with Arg398 in 81% of mammalian P450s. Here we report on the effect of the Trp/Arg cation−π interaction on Trp96 formal potentials as well as on electronic coupling strengths between Trp96 and the heme both for wild type cytochrome P450 and selected mutants. Mutation of Arg398 to His, which decreases the Trp96 formal potential, increases Trp-heme electronic coupling; however, surprisingly, the rate of phototriggered electron transfer from a Ru-sensitizer (through Trp96) to the P450 BM3 heme was unaffected by the Arg398His mutation. We conclude that Trp96 has moved away from Arg398, suggesting that the protective mechanism for P450s with this Trp-Arg pair is conformationally gated.
Targeted alpha therapy (TAT) relies on chemical affinity or active targeting using radioimmunoconjugates as strategies to deliver alpha-emitting radionuclides to cancerous tissue. These strategies ...can be affected by transmetalation of the parent radionuclide by competing ions in vivo and the bond-breaking recoil energy of decay daughters. The retention of alpha-emitting radionuclides and the dose delivered to cancer cells are influenced by these processes. Encapsulating alpha-emitting radionuclides within nanoparticles can help overcome many of these challenges. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles are a biodegradable and biocompatible delivery platform that has been used for drug delivery. In this study, PLGA nanoparticles are utilized for encapsulation and retention of actinium-225 (.sup.225AcAc.sup.3+). Encapsulation of .sup.225AcAc.sup.3+ within PLGA nanoparticles (Z.sub.ave = 155.3 nm) was achieved by adapting a double-emulsion solvent evaporation method. The encapsulation efficiency was affected by both the solvent conditions and the chelation of .sup.225AcAc.sup.3+. Chelation of .sup.225AcAc.sup.3+ to a lipophilic 2,9-bis-lactam-1,10-phenanthroline ligand (.sup.225AcAcBLPhen) significantly decreased its release (< 2%) and that of its decay daughters (< 50%) from PLGA nanoparticles. PLGA nanoparticles encapsulating .sup.225AcAcBLPhen significantly increased the delivery of .sup.225AcAc.sup.3+ to murine (E0771) and human (MCF-7 and MDA-MB-231) breast cancer cells with a concomitant increase in cell death over free .sup.225AcAc.sup.3+ in solution. These results demonstrate that PLGA nanoparticles have potential as radionuclide delivery platforms for TAT to advance precision radiotherapy for cancer. In addition, this technology offers an alternative use for ligands with poor aqueous solubility, low stability, or low affinity, allowing them to be repurposed for TAT by encapsulation within PLGA nanoparticles.
Naloxone is a medication with a largely benign safety profile that is frequently administered in the emergency department to patients presenting with altered mental status. Ventricular tachycardia ...has been reported after naloxone administration in adult patients with prior use of opiate or sympathomimetic medications. However, no such reports exist in the pediatric population or in patients who have no known history of opiate or sympathomimetic medication use. We describe a case of ventricular tachycardia after naloxone administration in a 17-year-old male with no known prior use of opiate or sympathomimetic agents who presented to the emergency department with altered mental status of unknown etiology. Emergency physicians may wish to prepare for prompt treatment of ventricular arrythmias when administering naloxone to pediatric patients presenting with altered mental status.
This work describes an analytical procedure, single particle-inductively coupled plasma-time-of-flight-mass spectrometry (SP-ICP-TOF-MS), that was developed to determine the platinum binding ...efficiency of protein-coated magnetic microparticles. SP-ICP-TOF-MS is advantageous due to its ability to quasi-simultaneously detect all nuclides (
7
Li-
242
Pu), allowing for both platinum and iron (composition of magnetic microparticles) to be measured concurrently. This method subsequently allows for the differentiation between bound and unbound platinum. The 1 μm magnetic microparticles were fully characterized for their iron concentration, particle concentration, and trace element composition by bulk digestion-ICP-MS and SP-ICP-TOF-MS. The results of both approaches agreed with the certificate values. Using the single particle methodology the platinum loading was quantified to be to 0.18 ± 0.02 fg per particle and 0.32 ± 0.02 fg per particle, for the streptavidin-coated and azurin-coated microparticles, respectively. Both streptavidin-coated and the azurin-coated microparticles had a particle-platinum association of >65%. Platinum bound samples were also analyzed
via
bulk digestion-based ICP-MS. The bulk ICP-MS results overestimated platinum loading due to free platinum in the samples. This highlights the importance of single particle analysis for a closer inspection of platinum binding performance. The SP-ICP-TOF-MS approach offers advantages over typical bulk digestion methods by eliminating laborious sample preparation, enabling differentiation between bound/unbound platinum in a solution, and quantification of platinum on a particle-by-particle basis. The procedure presented here enables quantification of metal content per particle, which could be broadly implemented for other single particle applications.
This work describes an analytical procedure, single particle-inductively coupled plasma-time-of-flight-mass spectrometry (SP-ICP-TOF-MS), that was developed to determine the platinum binding efficiency of protein-coated magnetic microparticles.
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