Evidence for β-turn structure in model peptides reproducing pro-ocytocin/neurophysin proteolytic processing site
1990; Elsevier BV; Volume: 168; Issue: 3 Linguagem: Inglês
10.1016/0006-291x(90)91138-i
ISSN1090-2104
AutoresMohamed Rholam, Paul A. Cohen, N. Brakch, Livio Paolillo, Angelo Scatturin, Carlo Di Bello,
Tópico(s)Neuropeptides and Animal Physiology
ResumoThe structural organization of small peptides reproducing the amino acid sequence of the common ocytocin/neurophysin precursor around the LysArg cleavage locus was investigated by a combination of spectroscopical techniques. In water both circular dichroism and [1H] NMR spectra indicated that these peptides adopted a random conformation. Evidence for folded structures was obtained when these compounds were placed in a membrane-like environment i.e. 40 mM SDS in phosphate buffer or trifluoroethanol. Whereas the CD spectra indicated the formation of various types of beta-turn in rapid equilibrium, measurements of NH temperature coefficients and Nuclear Overhauser Effects by 400 and 500 MHz NMR revealed the existence of contacts and of a folded conformation. These observations are discussed in relation with previous hypothesis made on the secondary structure organization of the proteolytic processing site of polypeptide hormone precursors.
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