Proteomics-Based Discovery of First-in-Class Chemical Probes for Programmed Cell Death Protein 2 (PDCD2)

Chemical probes are essential tools for understanding biological systems and for credentialing potential biomedical targets. Programmed cell death 2 (PDCD2) is a member of the B-cell lymphoma 2 (Bcl-2) family of proteins, which are critical regulators of apoptosis. Here we report the discovery and characterization of 10 e , a first-in-class small molecule degrader of PDCD2. We discovered this PDCD2 degrader by serendipity using a chemical proteomics approach, in contrast to the conventional approach for making bivalent degraders starting from a known binding ligand targeting the protein of interest. Using 10 e as a pharmacological probe, we demonstrate that PDCD2 functions as a critical regulator of cell growth by modulating the progression of the cell cycle in T lymphoblasts. Our work provides a useful pharmacological probe for investigating PDCD2 function and highlights the use of chemical proteomics to discover selective small molecule degraders of unanticipated targets.     

Cyclopropane-derived peptidomimetics. Design, synthesis, and evaluation of novel enkephalin analogues

It is known that peptide mimics containing trans-substituted cyclopropanes stabilize extended conformations of oligopeptides, and molecular modeling studies now suggest that the corresponding cis-cyclopropane dipeptide isosteres could stabilize a reverse turn. To begin to assess this possibility, a series of cis-substituted cyclopropanes were incorporated as replacements of the Gly(2)-Gly(3) and Phe(4)-Leu(5) dipeptide subunits in Leu-enkephalin (H(2)N-Tyr-Gly-Gly-Phe-Leu-OH), which is believed to bind to opiod receptors in a conformation containing a beta-turn. General methods for the synthesis of the cyclopropane-containing dipeptide isosteres -XaaPsi[COcpCO]Yaa- and -XaaPsi[NHcpNH]Yaa-were developed by a sequence that featured the enantioselective cyclization of allylic diazoacetates catalyzed by the chiral rhodium complexes Rh(2)[(5S)-MEPY](4) and Rh(2)[(5R)-MEPY](4). A useful modification of the Weinreb amidation procedure was applied to the opening of the intermediate lactones with dipeptides, and a novel method for the synthesis of substituted diaminocyclopropanes was also developed. The Leu-enkephalin analogues were tested in a panel of binding and functional assays, and although those derivatives containing cyclopropane replacements of the Gly(2)-Gly(3) exhibited low micromolar affinity for the mu-receptor, analogues containing such replacements for the Phe(4)-Leu(5) subunit did not bind with significant affinity to any of the opioid receptors. These results are discussed.     

Simulation of three-phase displacement experiments

Three-phase displacement experiments for a water-benzyl alcohol-decane system are simulated. Literature experimental three-phase relative permeabilities for the system are used to describe the relative permeabilities in the three-phase region for different three-phase relative permeability models. Saturation trajectories and elliptical regions are mapped in the three-phase region. Simulations are performed to model displacement experiments including breakthrough and the formation of multiple shocks. The model can be used to predict the results for other displacements. In an experiment where significant gravity segregation is present, the displacement is more accurately modeled by assuming a uniform initial condition than by using the actual vertical saturation and assuming no cross flow. It is shown how different residual saturation values can be measured in the laboratory depending on the initial saturation conditions in the core. The experimental residual saturations can be significantly different than the ‘theoretical’ or model values.     

Applicability of generic linear scoring mosels in the U.S. credit-union environment

Although credit-scoring models represent a widely used managerialaid for large financial intermediaries, the vast majority ofU.S. credit unions—relatively small cooperatively ownedretail intermediaries, constrained by sample and funding limitations—haveyet to adopt such techniques. Lovie & Lovie (1986) havetheorized that the flat-maximum effect or curve of insensitivityassociated with linear scoring models could be advantageousin areas of applied prediction such as credit scoring. In thiscontext, we reported the relative predictive power of genericcredit-scoring models versus customized models in an earlierpaper (Overstreet et al. 1992). Unfortunately, these findingswere not readily adaptable to the credit-union industry dueto a dated sample with incomplete credit-bureau information.Consequently, from 1988 to 1991, we gathered a refined databasefrom which to further develop and field-test generic scoringmodels in the credit-union environment. The results reportedherein not only confirm, but amplify, the relative predictivepower of such models found earlier. Relative costs and benefitsof generic versus customized models are modelled for a representativecredit union. Future research directions are set forth in theconclusions.     

Polymerization (Polycondensation) of Alkanes over Fluosulfonic Acid and Antimony Pentafluoride

Several low molecular weight alkanes have been polymerized (polycondensed) over HSO₃ F-SbF₅ to yield a highly branched oily oligomer with a molecular weight range from the molecular weight of the monomer to around 700. The order of reactivity for butane and lower molecular alkanes is isobutane > n-butane > propane > ethane > methane. The reactivity is explained by the ease of attack of an acid proton derived from the acid on the alkane sigma bonds as well as the relative stability of the resulting cation formed. A cationic mechanism for this reaction is proposed.