Peptaibols as a model for the insertions of chemical modifications.

Peptaibols are linear non ribosomal peptides which have been the object of intense research efforts regarding their synthesis and the elucidation of the mechanism allowing their insertion in biological membranes. Forty years after their discovery they are still considered as model compounds and suitable probes for the investigation of new approaches aiming to test the efficacy of new coupling reagents, to physically and spectroscopically investigate the way by which they interact with the lipid bilayer and to develop artificial membrane pores. The stable helical secondary structure adopted by the peptaibols turn to be an adequate platform for gaining insight on the structural modifications induced by the substitution of the amide bond by 1,2,3-triazoles, but also for monitoring the impact of newly designed α,α-dialkyl glycine with fluorinated and silylated side chains as 2-aminoisobutyric acid mimic. Peptaibols secondary structure dictated by Aib high content has inspired the development of foldamers. Challenges and investigations on the above mentioned topics are discussed in this brief review.

Trichormamide C Structural Confirmation through Total Synthesis and Extension to Analogs.

The growing interest in marine natural substances as potential new drugs has made total synthesis a real asset for structure confirmation. Trichormamide C (1), a cyclic lipopeptide isolated from the cyanobacteria Oscillatoria sp., is characterized by the presence of nonproteinogenic amino acids in the sequence. Trichormamide C structural confirmation was carried out through the implementation of a flexible synthesis resulting in two new analogs (3 and 4).

Molecular, Structural, Functional, and Pharmacological Sites for Vesicular Glutamate Transporter Regulation.

Vesicular glutamate transporters (VGLUTs) control quantal size of glutamatergic transmission and have been the center of numerous studies over the past two decades. VGLUTs contain two independent transport modes that facilitate glutamate packaging into synaptic vesicles and phosphate (Pi) ion transport into the synaptic terminal. While a transmembrane proton electrical gradient established by a vacuolar-type ATPase powers vesicular glutamate transport, recent studies indicate that binding sites and flux properties for chloride, potassium, and protons within VGLUTs themselves regulate VGLUT activity as well. These intrinsic ionic binding and flux properties of VGLUTs can therefore be modulated by neurophysiological conditions to affect levels of glutamate available for release from synapses. Despite their extraordinary importance, specific and high-affinity pharmacological compounds that interact with these sites and regulate VGLUT function, distinguish between the various modes of transport, and the different isoforms themselves, are lacking. In this review, we provide an overview of the physiologic sites for VGLUT regulation that could modulate glutamate release in an over-active synapse or in a disease state.