ABSTRACT
The interaction between two Lewis "superacid" catalysts Zn(OTf)(2) and In(OTf)(3) and series of amide and phosphate ligands is quantitatively characterized by electrospray ionization mass spectrometry (ESI-MS). A specific feature of the ESI-MS spectra of the mixture of metal triflates and Lewis bases is the formation of ionic adducts resulting from the displacement of one triflate anion by two neutral ligands. A ligand competition model is developed, which describes the relative intensities of the ionic adducts as a function of relative ligand concentrations. The relative affinities deduced from the ligand competition method are combined in an affinity scale for the metal triflate.
ABSTRACT
We report a second example of a general reaction screening approach to discover low molecular weight inhibitors of protein protein interactions. On the basis of the known pharmacophore model of SMAC mimetics, we predicted several inhibitors based on four different multicomponent reactions. The predicted inhibitors were subsequently synthesized, tested, and found to bind to the antiapoptotic protein X-linked inhibitor of apoptosis protein (XIAP) and showed cellular activity. Also the compounds are currently not highly potent. They could form a starting point for future medicinal chemistry optimization.
Subject(s)
Antineoplastic Agents/chemistry , Models, Molecular , Peptidomimetics/chemistry , X-Linked Inhibitor of Apoptosis Protein/antagonists & inhibitors , Amino Acid Motifs , Amino Acid Sequence , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cell Survival/drug effects , Databases, Factual , Drug Screening Assays, Antitumor , Humans , Peptidomimetics/chemical synthesis , Peptidomimetics/pharmacology , Piperazines/chemical synthesis , Piperazines/chemistry , Piperazines/pharmacology , Protein Binding , Stereoisomerism , Structure-Activity Relationship , Tetrazoles/chemical synthesis , Tetrazoles/chemistry , Tetrazoles/pharmacology , Thiazoles/chemical synthesis , Thiazoles/chemistry , Thiazoles/pharmacology , Thiazolidines/chemical synthesis , Thiazolidines/chemistry , Thiazolidines/pharmacology , X-Linked Inhibitor of Apoptosis Protein/chemistry , X-Linked Inhibitor of Apoptosis Protein/metabolismABSTRACT
The relative Lewis basicity of a series of phosphoryl compounds toward cations M(n+)(OTf)(n-1) derived from triflate salts, M(OTf)(n), is ranked using electrospray mass spectrometry according to competitive adduct formation.
Subject(s)
Lewis Acids/chemistry , Metals/chemistry , Catalysis , Hydrogen-Ion Concentration , Phosphates/chemistry , Spectrometry, Mass, Electrospray IonizationABSTRACT
Trifluoromethylsulfonate (triflate) and bis(trifluoromethylsulfonyl)imide (triflimide) salts, well-known Lewis acid catalysts, present some difficulty in their characterization. By using nitromethane as the solvent, useful electrospray mass spectra in positive and negative ion mode were obtained for salts of metals in oxidation states +2 and +3. In positive mode, addition of a strong Lewis base (triphenylphosphine oxide, TPPO), capable of displacing a triflate (TfO(-)) or a triflimide (Tf(2)N(-)) anion, is necessary for obtaining useful spectra. Under these conditions of solvent and added ligand, the most abundant ions were [M(2+)(A(-))(TPPO)(2)](+) or [M(3+)(A(-))(2)(TPPO)(2)](+) with A(-) = TfO(-) or Tf(2)N(-). The MS/MS spectra of these diagnostic ions provide additional analytical information. The breakdown curves, in the form of % dissociated as a function of the ion activation energy, offer a mean for investigating the bonding in these ions.
ABSTRACT
A very short convergent synthesis of dihydrobenzoxazepinones, bearing four diverse diversity points, based on coupling the Ugi reaction with a Mitsunobu cyclization, was developed. These compounds are potential α-helix mimics, where three of the four appendages are expected to imitate the residues in i, i + 4 and i + 7 positions. A library of 22 compounds bearing lipophilic substituents, designed to interact with the hydrophobic cleft of anti-apoptotic protein Bcl-xL, was synthesized. Preliminary biochemical tests, based on competitive binding, have already been carried out.
Subject(s)
Chemistry, Organic/methods , Heterocyclic Compounds, 3-Ring/chemical synthesis , Protein Structure, Secondary , Alcohols/chemical synthesis , Alcohols/chemistry , Heterocyclic Compounds, 3-Ring/chemistry , Humans , Magnetic Resonance Spectroscopy , Models, Molecular , Salicylic Acid/chemical synthesis , Salicylic Acid/chemistryABSTRACT
BH3-only members of the Bcl-2 family exert a fundamental role in apoptosis induction. This work focuses on the development of a novel peptidic molecule based on the BH3 domain of Bim. The antiapoptotic molecule Bcl-X(L), involved in cancer development/progression and tumour resistance to cytotoxic drugs, is a target for Bim. According to a rational study of the structural interactions between wt Bim-BH3 and Bcl-X(L), we replaced specific residues of Bim-BH3 with natural and non-natural aminoacids and added an internalizing sequence, thus increasing dramatically the inhibitory activity of our modified Bim-BH3 peptide, called 072RB. Confocal microscopy and flow cytometry demonstrated cellular uptake and internalization of 072RB, followed by co-localization with mitochondria. Multiparameter flow cytometry demonstrated that the 072RB dose-dependent growth inhibition of leukaemia cell lines was due to apoptotic cell death. No effect was observed when cells were treated with the internalizing vector alone or a mutated control peptide (single aminoacid substitution L94A). Ex-vivo derived leukemic cells from acute myeloid leukaemia (AML) patients underwent cell death when cultured in vitro in the presence of 072RB. Conversely, no significant cytotoxic effect was observed when 072RB was administered to cultures of peripheral blood mononuclear cells, either resting or PHA-stimulated, and bone marrow cells of normal donors. Xenografts of human AML cells in NOD/SCID mice displayed a significant delay of leukemic cell growth upon treatment with 072RB administered intravenously (15 mg/Kg three times, 48 hours after tumour cell injection). Altogether, these observations support the therapeutic potentials of this novel BH3 mimetic.
Subject(s)
Apoptosis Regulatory Proteins/metabolism , Membrane Proteins/metabolism , Peptides/metabolism , Proto-Oncogene Proteins/metabolism , bcl-X Protein/antagonists & inhibitors , bcl-X Protein/metabolism , Amino Acid Sequence , Animals , Apoptosis/physiology , Apoptosis Regulatory Proteins/chemistry , Apoptosis Regulatory Proteins/genetics , Bcl-2-Like Protein 11 , Cells, Cultured , Female , Humans , Leukemia, Myeloid, Acute/metabolism , Lymphocytes/cytology , Lymphocytes/physiology , Membrane Proteins/chemistry , Membrane Proteins/genetics , Mice , Mice, Inbred NOD , Mice, SCID , Molecular Sequence Data , Neoplasm Transplantation , Peptides/chemistry , Peptides/genetics , Protein Structure, Tertiary , Proto-Oncogene Proteins/chemistry , Proto-Oncogene Proteins/genetics , Transplantation, Heterologous , Tumor Cells, Cultured , bcl-2-Associated X Protein/genetics , bcl-2-Associated X Protein/metabolism , bcl-X Protein/geneticsABSTRACT
The synthesis of new conformationally biased cyclic pentapeptides, incorporating the RGD sequence, and built around a tetrahydroazoninone scaffold, is reported. They exhibit interesting activity towards integrin alphaVbeta3 and a remarkable selectivity in comparison with integrin alphaVbeta5.