1,721,042 research outputs found
SALICYLALDEHYDE-TAGGED PEPTIDES FOR THE REVERSIBLE-COVALENT ENGAGEMENT OF PROTEIN LYSINE RESIDUES
Full text linkInserting electrophilic species into small molecule ligands or peptides is a well-established method for enhancing binding affinity to target proteins. The amino acid Lysine (Lys) is highly abundant in the proteome and one of the most frequent residues on the outer structural layers of proteins. For these reasons, the derivatization of synthetic ligands with aldehyde tags capable of imine bond formation with Lys ɛ-amino groups may represent a general strategy for the discovery of potent small-molecule inhibitors.
Ortho-hydroxy aldehydes such as pyridoxal or salicylaldehyde (SA) derivatives have been used to form imines in aqueous media, stabilized by an intramolecular H-bond between the imine N atom and the ortho-phenolic proton. By virtue of this reactivity, SA derivatives are being installed into various classes of protein ligands, aimed at the reversible-covalent engagement of protein Lys residues.1,2
This talk will describe our recent contribution to this field, with focus on the installation of the Lys-engaging SA module into peptide ligands.3,4
Figure 1. Left: Binding mechanism of a reversible-covalent ligand equipped with a salicylaldehyde (SA) tag. Ideally, SA forms a remarkably stable imine bond with a Lys(ε-NH2) residue proximal to the ligand binding site. This covalent ligand-protein connection is stabilized by a H bond between the OH phenolic proton and the imine N atom. As a result, the final ligand-protein complex is stabilized by a combination of non-covalent and covalent interactions. Right: Current options for the SA tag installation at different peptide positions, recently developed by our group.
References
1. A. Dal Corso, M. Catalano, A. Schmid, J. Scheuermann, D. Neri, Angew. Chem. Int. Ed. 2018, 57, 17178.
2. M. Mason, L. Belvisi, L. Pignataro, A. Dal Corso, ChemBioChem 2023, e202300743.
3. G. Sacco, D. Arosio, M. Paolillo, A. Gloger, J. Scheuermann, L. Pignataro, L. Belvisi, A. Dal Corso, C. Gennari, Chem. Eur. J. 2023, e202203768.
4. M. Mason, B. Nava, L. Belvisi, L. Pignataro, A. Dal Corso, Eur. J. Org. Chem. 2024, 27, 202400229
Electron-vibration coupling constants in positively charged fullerene
No full textRecent experiments have shown that C-60 can be positively field doped. In that state, fullerene exhibits a higher resistivity and a higher superconducting temperature than the corresponding negatively doped state. A strong intramolecular hole-phonon coupling, connected with the Jahn-Teller effect of the isolated positive ion, is expected to be important for both properties, but the actual coupling strengths are so far unknown. Based on density functional calculations, we determine the linear couplings of the two a(g), six g(g) and eight h(g) vibrational modes to the H-u highest occupied molecular orbital level of the C-60 molecule. The couplings predict a D-5 distortion, and an H-u vibronic ground state for C-60(+). They are also used to generate the dimensionless coupling constant lambda which controls the superconductivity and the phonon contribution to the electrical resistivity in the crystalline phase. We find that lambda is 1.4 times larger in positively charged C-60 than in the negatively doped case. These results are discussed in the context of the available transport data and superconducting temperatures. The role of higher orbital degeneracy in superconductivity is also addressed
αvβ3 integrin-targeted peptide/peptidomimetic-drug conjugates: in-depth analysis of the linker technology
Full text linkCovalent conjugation of anticancer drugs to targeting carriers (e.g., antibodies or small molecules) capable of selectively binding to tumor-specific antigens, is emerging as a successful strategy to overcome the drawbacks of traditional chemotherapy. Due to its overexpression on blood vessels of human tumors, αvβ3 integrin is one of the most studied receptors of tumor-targeted therapeutics: several peptides and peptidomimetics, bearing the RGD (Arg-Gly-Asp) recognition sequence, have been developed as integrin ligands and linked to different anticancer drugs. The resulting integrintargeted small molecule-drug conjugates (SMDCs) are able to release the cytotoxic agents upon cleavage of a linker under specific conditions (i.e., hydrolysis, enzymatic action or reduction). Despite the significant efforts made in this field, αvβ3 integrin-targeted SMDCs are still far from the clinic. In this review, we survey this approach with a special focus on the different linkers employed and the reported biological activities in vitro and in vivo
TUMOR TARGETING VIA INTEGRIN LIGANDS: SYNTHESIS AND BIOLOGICAL EVALUATION OF RGD PEPTIDOMIMETIC-DRUG CONJUGATES
Full text linkPeptides and peptidomimetics bearing the Arg-Gly-Asp peptide sequence have been demonstrated to bind with high affinity to αvβ3 Integrin, a heterodimeric transmembrane receptor overexpressed in several tumor cells. For these reasons, integrin ligands have been coupled to a variety of anticancer drugs, aiming at the selective delivery of the payload at the tumor site. This PhD work describes the conjugation of the peptidomimetic αvβ3 Integrin ligand cyclo[DKP-RGD] to different anticancer drugs (i.e. paclitaxel, daunorubicin and camptothecin) through peptide and disulfide linkers. The resulting small molecule-drug conjugates (SMDCs) are selective αvβ3 binders and are able to release the drug upon exposure to lysosomal enzymes (e.g. cysteine proteases) or intracellular reducing agents (e.g. glutathione). Cell proliferation assays against isogenic human cancer cells expressing αvβ3 at different levels (αvβ3 +/αvβ3 −) have been performed to evaluate the selective cytotoxic activity of RGD-based SMDCs against integrin-positive cancer cells. Fairly effective integrin targeting was displayed by the cyclo[DKP-RGD]-Val-Ala-PTX conjugate (compound 80), which was found to differentially inhibit proliferation in antigen-positive CCRF CEM αvβ3 versus antigen-negative isogenic CCRF-CEM cells. Next-generation cyclo[DKP-RGD]-Drug conjugates were prepared, aiming at improving the targeting effect shown by the cyclo[DKP-RGD]-Val-Ala-PTX conjugate as well as to deeply analyze the SMDC’s interactions with cancer cells
Heterologous production of five Hepatitis C Virus-derived antigens in three Saccharomyces cerevisiae host strains
No full textIn this study, the production of recombinant Hepatitis C virus (HCV) derived proteins from transformed Saccharomyces cerevisiae yeast cells is reported. Three different yeast strains (GRF18U, BY4743-4A and CENPK 113-5D) have been transformed for the intracellular expression of five antigens of different dimensions (from 32.8 to 85.2 kDa), all derived from the non-structural (NS) region of different HCV viruses' genotypes and posed under the control of a glycolytic promoter. The putative trans-membrane domains contained in four antigens seem responsible of their accumulation as protein aggregates. Good productions of the smaller and of the bigger antigens (50 and 30 mgl(-1), respectively) have been observed in simple flask batch cultures. Productions are strongly dependent from the genetic background of the yeast host and from the cellular localization of the antigen, while they appear independent from the growth rate of the transformed hosts. For every recombinant antigen tested, the highest production levels were achieved with the CENPK 113-5D-host strain, while the GRF18U strain shows symptoms of a heavily stressed phenotype
Synthesis and biological evaluation of RGD peptidomimetic-campthotecin conjugates with disulfide linkers
No full textConjugation of cytotoxic agents to targeting carriers (e.g. antibodies or small molecules) capable of selectively binding to tumor-specific antigens, is emerging as a successful strategy to overcome the drawbacks of traditional chemotherapy.[1] Being over-expressed by several human tumors, αvβ3 integrin can be considered as a suitable target for cancer therapy with small molecule-drug conjugates (SMDCs). The Arg-Gly-Asp (RGD) peptide sequence has been found to bind with high affinity to αvβ3 integrin: for these reasons, several RGD-bearing peptides and peptidomimetics have been investigated as promising carriers for the delivery of anticancer drugs.[2] The resulting SMDCs are able to release the anticancer agents upon cleavage of a linker, under the specific conditions of the tumor environment. Following this approach, our research group has recently developed two RGD-Paclitaxel conjugates containing dipeptide linkers that can be selectively cleaved by proteases.[3] Here, we report the development of new RGD conjugates containing the disulfide linker, which is stable in plasma but can be selectively cleaved by the reductants present in the cell. Two such RGD peptidomimetic-Campthotecin conjugates (compounds 2, 3) have been synthesized, and their ability to bind αvβ3 integrin has been evaluated. They exhibited high affinity for the αvβ3 integrin, with low-nanomolar IC50 values, comparable to that of the free ligand 1.[4] Further biological assays are in progress to evaluate the cytotoxicity of the new compounds against cancer cell lines expressing αvβ3 integrin at different levels
Synthesis of Non-Coded Amino Acids with a Salicylaldehyde Tag for Reversible-Covalent Peptides
Full text linkInserting electrophilic species into small molecule ligands or peptides is a well-established method for enhancing binding affinity to target proteins. The salicylaldehyde (SA) tag forms stable imine bonds with the ε-amino group of lysine, a common protein residue (10.1002/cbic.202300743). This study outlines the optimized synthesis of two new non-coded α-amino acids featuring the SA tag. These building blocks enable the flexible insertion of the SA tag into peptide sequences, facilitating the design of lysine-engaging ligands (10.1002/ejoc.202400229)
Synthesis and biological evaluation of new RGD-camptothecin conjugates bearing disulfide linkers
No full textConjugation of cytotoxic agents to targeting carriers (e.g. antibodies or small molecules) capable of selectively binding to tumor-specific antigens, is emerging as a successful strategy to overcome the drawbacks of traditional chemotherapy.[1] Being over-expressed by several human tumors, αvβ3 integrin can be considered as a suitable target for cancer therapy with small molecule-drug conjugates (SMDCs). The Arg-Gly-Asp (RGD) peptide sequence has been found to bind with high affinity to αvβ3 integrin: for these reasons, several RGD-bearing peptides and peptidomimetics have been investigated as promising carriers for the delivery of anticancer drugs.[2] The resulting SMDCs are able to release the anticancer agents upon cleavage of a linker, under the specific conditions of the tumor environment. Following this approach, our research group has recently developed two RGD-Paclitaxel conjugates containing dipeptide linkers that can be selectively cleaved by proteases.[3] Here, we report the development of new RGD conjugates containing the disulfide linker, which is stable in plasma but can be selectively cleaved by the reductants present in the cell. Two such RGD peptidomimetic-Campthotecin conjugates (compounds 2, 3) have been synthesized, and their ability to bind αvβ3 integrin has been evaluated. They exhibited high affinity for the αvβ3 integrin, with low-nanomolar IC50 values, comparable to that of the free ligand 1.[4] Further biological assays are in progress to evaluate the cytotoxicity of the new compounds against cancer cell lines expressing αvβ3 integrin at different levels
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