Evidence for beta-turn structure in model peptides reproducing pro-ocytocin/neurophysin proteolytic processing site.
The 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.
Rholam
M
M
Université Pierre et Marie Curie, URA 554 du CNRS, Paris, France.
Cohen
P
P
Brakch
N
N
Paolillo
L
L
Scatturin
A
A
Di Bello
C
C
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009481:Neurophysins / Q000378:metabolism*; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000378:metabolism; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D011487:Protein Conformation
D009481:Neurophysins; D009842:Oligopeptides; D010121:Oxytocin; C046278:oxytocin, Gly-Lys-Arg-; D010447:Peptide Hydrolases