Portal de Periódicos da CAPES

Synthesis and conformational studies of peptides containing TOAC, a spin‐labelled C α,α ‐disubstituted glycine

1995; Wiley; Volume: 1; Issue: 1 Linguagem: Inglês

10.1002/psc.310010107

1099-1387

Claudio Toniolo, E. Valente, Fernando Formaggio, Marco Crisma, Giuseppe Pilloni, Carlo Corvaja, Antonio Toffoletti, Gary V. Martinez, MA Hanson, Glenn L. Millhauser, Clifford George, J.L. Flippen-Anderson,

Mass Spectrometry Techniques and Applications

Abstract A variety of host L ‐alanine homo‐peptides (to the pentamer) containing one or two spin‐labelled TOAC (2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐4‐amino‐4‐carboxylic acid) residues were synthesized by solution methods and fully characterized. The conformational features of the terminally blocked, doubly spin‐labelled–TOAC–(Ala) 2 –TOAC–Ala– pentapeptide were examined in the crystal state by X‐ray diffraction and in solution using a combination of techniques (Fourier transform infrared, circular dichroism, cyclic voltammetry and electron spin resonance) in comparison with singly labelled shorter peptides. The 3 10 ‐helical structure of the pentapeptide, promoted by the two C α,α ‐disubstituted glycines under favourable experimental conditions, allows an interaction to take place between the two nitroxide TOAC side chains spaced by one turn of the helix. Taken together, these results suggest that TOAC is an excellent probe for exploring bends and helices in doubly labelled peptides.