title: Periodic properties of proton conformational shifts in isolated protein helices. An experimental study.
abstract: In this work, the helix-forming residues in fragments of several proteins (ribonuclease, thermolysin, tendamistat and angiogenin) were identified by NOE and the helix proton shifts were measured as delta changes associated with helix-population increments driven by trifluoroethanol addition. When estimated in this way, a regular pattern of helix conformational shifts was clearly seen in the delta delta versus sequence profiles of all the peptides studied. The helix periodicity of the H alpha and H beta resonances was especially clear, an observation that earlier statistical studies of protein delta values failed to predict. Amide protons showed the largest helix shifts, but with a less-sharply defined periodic character. Aromatic residues considerably distorted the periodicity of the helix amide shifts in some peptides, as evidenced by the delta shifts of a RNase A fragment 1-15 analog in which the two aromatic residues were replaced by Ala. The relationship between helix periodicity and peptide amphiphatic character is discussed.
authors.affiliation: Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Jiménez
authors.forename: F J
authors.initials: FJ
authors.lastname: Blanco
authors.forename: M
authors.initials: M
authors.lastname: Rico
authors.forename: J
authors.initials: J
authors.lastname: Santoro
authors.forename: J
authors.initials: J
authors.lastname: Herranz
authors.forename: J L
authors.initials: JL
authors.lastname: Nieto
mesh_terms: D000595:Amino Acid Sequence; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D012259:Ribonuclease, Pancreatic; D012260:Ribonucleases / Q000737:chemistry; D013820:Thermolysin / Q000737:chemistry; D000516:alpha-Amylases / Q000037:antagonists & inhibitors
chemical_list: D009842:Oligopeptides; D010446:Peptide Fragments; D010455:Peptides; D011506:Proteins; D012260:Ribonucleases; C046366:angiogenin; D012259:Ribonuclease, Pancreatic; D000516:alpha-Amylases; D013820:Thermolysin; C030526:tendamistate