Optimized selective N-methylation of peptides on solid support

Diketopiperazines as a Tool for the Study of Transport across the Blood−Brain Barrier (BBB) and Their Potential Use as BBB-Shuttles

Here we prepared and evaluated two libraries of mono-N-methylated and di-N-methylated diketopiperazines (DKPs) by parallel artificial membrane permeability assay and immobilized artificial membrane chromatography in order to obtain information on the features that govern the passage of peptidic molecules across the blood-brain barrier (BBB) by passive diffusion. On the basis of the results from these two libraries, we prepared and evaluated several DKP-baicalin and DKP-dopamine constructs. The DKPs or cyclic dipeptide scaffolds can be considered a novel family of brain delivery systems (BBB-shuttles) to transport to the brain drugs and other cargos that cannot cross the BBB unaided.

Structure of the transmembrane signal initiation site of the relaxin-like factor (RLF/INSL3)

We have discovered the signal initiation structure of the relaxin-like factor and shown its function to be independent of the amino acid side chains in the contact region. Evidence presented in this article suggests that signal induction is a function of the peptide bond and that completion of the signaling contact is initiated by ligand binding to the leucine-rich repeat G-protein coupled receptor 8 (LGR8). The specific mode of binding forces certain peptide bonds into a signaling position. This observation implies that the receiving structures are equally nonspecific so that signaling should occur at any peptide bond of the receptor or the trans-membrane loop that is within reach of the signaling wires of the receptor-bound ligand. Our observations offer an explanation for ligand cross-talk as well as for the ability of some antibodies to elicit the biological response normally associated with a specific ligand.

Photochemically-activated probes of protein-protein interactions

The activity of light-activatable ("caged") compounds can be temporally and spatially controlled, thereby providing a means to interrogate intracellular biochemical pathways as a function of time and space. Nearly all caged peptides contain photocleavable groups positioned on the side chains of key residues. We describe an alternative active site targeted strategy that disrupts the interaction between the protein target (SH2 domain, kinase, and proteinase) and a critical amide NH moiety of the peptide probe.

Novel synthon for incorporating 1,3-dimethyl imidazolium group into molecular architecture

The synthesized 1,3-dimethylated imidazolium carbaldehydes serves as synthons for incorporating a permanently cationic imidazolium group into molecular framework. The utility of new synthon was demonstrated in a variety of reactions: Knoevenagel, Wittig, Schiff base formation, based mediated electrophilic substitution and oxidation, including synthesis of the natural product norzooanemonin.