title: Low-temperature 1H-NMR evidence of the folding of isolated ribonuclease S-peptide.
abstract: The temperature (-7 degrees C to 45 degrees C, pH 5.4) and pH (0 degrees C) dependence of 1H chemical shifts of ribonuclease S-peptide (5 mM, 1 M NaCl) has been measured at 360 MHz. The observed variations evidence the formation of a partial helical structure, involving the fragment Thr-3-Met-13. Two salt-bridges stabilize the helix: those formed by Glu-9- ...His-12+ and Glu-2- ...Arg-10+. The structural features deduced from the 1H-NMR at low temperature for the isolated S-peptide are compatible with the structure shown by the same molecule in the ribonuclease S crystal.
mesh_terms: D000595:Amino Acid Sequence; D055598:Chemical Phenomena; D002621:Chemistry; D009682:Magnetic Resonance Spectroscopy; D010446:Peptide Fragments / Q000302:isolation & purification*; D011487:Protein Conformation; D012260:Ribonucleases / Q000302:isolation & purification*; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D010446:Peptide Fragments; C023560:ribonuclease S-peptide; D012260:Ribonucleases