Periodic properties of proton conformational shifts in isolated protein helices. An experimental study.
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.
Jiménez
M A
MA
Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Blanco
F J
FJ
Rico
M
M
Santoro
J
J
Herranz
J
J
Nieto
J L
JL
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
D009842:Oligopeptides; D010446:Peptide Fragments; D010455:Peptides; D011506:Proteins; D012260:Ribonucleases; C046366:angiogenin; D012259:Ribonuclease, Pancreatic; D000516:alpha-Amylases; D013820:Thermolysin; C030526:tendamistate