Navigating complex peptide structures using macrocycle conformational maps.

Identification of turn motifs that are stabilized by intramolecular hydrogen bonds can be useful in describing the conformation of peptide systems. However, this approach is somewhat insufficient for cyclic peptides because peptide regions that are not positioned within a hydrogen bond can be left with no description. Furthermore, non-regular secondary structures and other rarely-observed conformations can be left without detailed evaluation. Herein, we describe "higher-order" ϕ/ψ plots termed macrocycle conformational maps (MCMs) as a tool for evaluating and comparing the conformations of a series of structurally related macrocyclic peptides.

Concentrated Aqueous Peroxodicarbonate: Efficient Electrosyn- thesis and Use as Oxidizer in Epoxidations, S-, and N-Oxidations.

Peroxodicarbonates are of substantial interest as potentially powerful and sustainable oxidizers but have so far been accessible only in low concentrations with unsatisfactory energy efficiency. Concentrated (> 0.9 mol L-1 ) peroxodicarbonate solutions have now been made accessible by the electrolysis of aqueous K2 CO3 /Na2 CO3 /KHCO3 solutions at high current density of 3.33 A cm-2 in an efficiently cooled circular flow reactor equipped with a boron-doped diamond anode and a stainless-steel cathode. Their synthetic potential as platform oxidizers was clearly demonstrated in transformations including sulfoxidation, N-oxidation, and epoxidation.