Synthesis and conformational characterisation of hexameric β-peptide foldamers by using double POAC spin labelling and cw-EPR.

A selected set of terminally protected β-hexapeptides, each containing two nitroxide-based (3R,4R)-4-amino-1-oxyl-2,2,5,5-tetramethylpyrrolidine-3-carboxylic acid (POAC) residues combined with four (1S,2S)-2-aminocyclopentane-1-carboxylic acid (ACPC) residues, was synthesised by using solution methods and was fully characterised. The two POAC residues are separated in the sequences by different numbers of intervening ACPC residues. The conformational features of the doubly spin-labelled β-hexapeptides were examined in chloroform by FTIR absorption and continuous-wave electron paramagnetic resonance spectroscopic techniques.

A new tool for photoaffinity labeling studies: a partially constrained, benzophenone based, alpha-amino acid.

The novel alpha-amino acid BpAib, a partially conformationally restricted analogue of the currently extensively used 3-(4-benzoylphenyl)alanine (Bpa) photoaffinity label, was synthesized, optically resolved, fully characterized, and appropriately derivatized. An intermolecular photocrosslinking experiment highlighted its regioselective reactivity towards the S-methyl side-chain group of a Met-based dipeptide, which is closely comparable to that of Bpa.

Substituted aryl malonamates as new serine beta-lactamase substrates: structure-activity studies.

A series of substituted aryl malonamates have been prepared. These compounds are analogues of aryl phenaceturates where the amido side chain has been replaced by a retro-amide. Like the phenaceturates, these compounds are substrates of typical class A and class C beta-lactamases, particularly of the latter, and of soluble DD-peptidases.