Truncated and Helix-Constrained Peptides with High Affinity and Specificity for the cFos Coiled-Coil of AP-1

Protein-based therapeutics feature large interacting surfaces. Protein folding endows structural stability to localised surface epitopes, imparting high affinity and target specificity upon interactions with binding partners. However, short synthetic peptides with sequences corresponding to such protein epitopes are unstructured in water and promiscuously bind to proteins with low affinity and specificity. Here we combine structural stability and target specificity of proteins, with low cost and rapid synthesis of small molecules, towards meeting the significant challenge of binding coiled coil proteins in transcriptional regulation. By iteratively truncating a Jun-based peptide from 37 to 22 residues, strategically incorporating i-->i+4 helix-inducing constraints, and positioning unnatural amino acids, we have produced short, water-stable, alpha-helical peptides that bind cFos. A three-dimensional NMR-derived structure for one peptide (24) confirmed a highly stable alpha-helix which was resistant to proteolytic degradation in serum. These short structured peptides are entropically pre-organized for binding with high affinity and specificity to cFos, a key component of the oncogenic transcriptional regulator Activator Protein-1 (AP-1). They competitively antagonized the cJun–cFos coiled-coil interaction. Truncating a Jun-based peptide from 37 to 22 residues decreased the binding enthalpy for cJun by ~9 kcal/mol, but this was compensated by increased conformational entropy (TDS ≤ 7.5 kcal/mol). This study demonstrates that rational design of short peptides constrained by alpha-helical cyclic pentapeptide modules is able to retain parental high helicity, as well as high affinity and specificity for cFos. These are important steps towards small antagonists of the cJun-cFos interaction that mediates gene transcription in cancer and inflammatory diseases

Asymmetric triplex metallohelices with high and selective activity against cancer cells

Small cationic amphiphilic α-helical peptides are emerging as agents for the treatment of cancer and infection, but they are costly and display unfavourable pharmacokinetics. Helical coordination complexes may offer a three-dimensional scaffold for the synthesis of mimetic architectures. However, the high symmetry and modest functionality of current systems offer little scope to tailor the structure to interact with specific biomolecular targets, or to create libraries for phenotypic screens. Here, we report the highly stereoselective asymmetric self-assembly of very stable, functionalized metallohelices. Their anti-parallel head-to-head-to-tail ‘triplex’ strand arrangement creates an amphipathic functional topology akin to that of the active sub-units of, for example, host-defence peptides and ​p53. The metallohelices display high, structure-dependent toxicity to the human colon carcinoma cell-line HCT116 ​p53++, causing dramatic changes in the cell cycle without DNA damage. They have lower toxicity to human breast adenocarcinoma cells (MDA-MB-468) and, most remarkably, they show no significant toxicity to the bacteria methicillin-resistant Staphylococcus aureus and Escherichia coli. At a glanc

Copper-catalysed selective hydroamination reactions of alkynes

The development of selective reactions that utilize easily available and abundant precursors for the efficient synthesis of amines is a long-standing goal of chemical research. Despite the centrality of amines in a number of important research areas, including medicinal chemistry, total synthesis and materials science, a general, selective and step-efficient synthesis of amines is still needed. Here, we describe a set of mild catalytic conditions utilizing a single copper-based catalyst that enables the direct preparation of three distinct and important amine classes (enamines, α-chiral branched alkylamines and linear alkylamines) from readily available alkyne starting materials with high levels of chemo-, regio- and stereoselectivity. This methodology was applied to the asymmetric synthesis of ​rivastigmine and the formal synthesis of several other pharmaceutical agents, including ​duloxetine, ​atomoxetine, ​fluoxetine and ​tolterodine.National Institutes of Health (U.S.) (GM58160

Synthesis and anticancer activities of 6-amino amonafide derivatives.

Amonafide is a DNA intercalator and topoisomerase II inhibitor in clinical development for the treatment of neoplastic diseases. Amonafide contains a free arylamine, which causes it to be metabolized in humans by N-acetyl transferase-2 (NAT2) into a toxic form. To eliminate the NAT2 acetylation of amonafide while retaining the anticancer properties, we have synthesized nine derivatives that are structurally similar to amonafide that should not be acetylated. Eight derivatives have arylamines at the 6-position (vs. 5-position of amonafide) and one derivative completely lacks the arylamine. The derivative with a free amine in the 6-position and one with a substituted amine in the 6-position are not acetylated, whereas amonafide is extensively acetylated as determined by an NAT2 assay. The biological activities of these compounds were evaluated to determine whether they behaved similarly to amonafide in purified systems and in vitro. We found that three compounds had similar cancer cell-selective growth inhibition to amonafide, while retaining similar subcellular localization, DNA intercalation and topoisomerase II inhibition activities. In addition, these compounds were able to eliminate a marker of metastatic potential, the perinucleolar compartment. These three compounds (named numonafides) might thus allow for better patient management than those treated with amonafide; hence, they should be developed further as potential clinical replacements for amonafide or as novel anticancer drugs

Highly functionalized cyclic beta-amino acid moieties as promising scaffolds in peptide research and drug design

Peptide-based drug research has received high attention in the field of medicinal chemistry over the past decade. For drug design, to improve proteolytic stability, it is desirable to include unnatural building blocks, such as conformationally restricted beta-amino acid moieties, into the peptide sequence. Accordingly, the synthesis and incorporation of such conformationally rigid systems into novel type of peptides has gained large interest. Our research group has designed highly efficient methods for the construction of potential antimicrobial peptides. Moreover, a number of synthetic approaches have been developed for the synthesis of various pharmacologically interesting cyclic beta-amino acid derivatives as monomers with multiple stereogenic centers

Molecular discrimination inside polymer nanotubules

Recognition of small organic molecules and large biomolecules such as proteins is of great importance in pharmaceutical as well as biological applications. Recognition inside a nanoporous membrane is particularly attractive, because of the advantages associated with ligand–receptor interactions in confined spaces. Classical nanoporous membrane-based separations simply use the difference in size of the analytes relative to pore size in the membrane. In order to bring about selectivity beyond size, it is necessary that methods for functionalizing the membrane pores are readily available. Here, we describe a simple approach to functionalize the nanopores within these membranes using self-assembling and non-self-assembling polymers. We show that these modified membranes separate small molecules based on size, charge and hydrophobicity. We also demonstrate here that proteins can be differentially transported through the nanopores based on their size and/or electrostatics