title: Proton NMR and photochemically induced dynamic nuclear polarization studies of peptide fragments obtained by controlled proteolysis of mouse epidermal growth factor.
abstract: Controlled proteolysis of epidermal growth factor from the mouse leads to fragments of mouse epidermal growth factor containing residues 1-48 and 1-45. The COOH-terminal pentapeptide appears to play a crucial role in determining the hydrophobic interactions between the hormone and the stationary phase during gel chromatography on TSK-125 gel. Proton NMR studies indicate that the overall structure of mouse epidermal growth factor is retained in the protein devoid of the COOH-terminal pentapeptide, while subsequent cleavage of the peptide bond between Arg-45 and Asp-46 starts to perturb the proton resonances most characteristic of the tertiary structure of the hormone, especially those from the aromatic ring protons of Tyr-37. Consequently, photochemically induced dynamic nuclear polarization experiments show an increased exposure of Tyr-37 in the fragment of mouse epidermal growth factor containing residues 1-48. Nuclear Overhauser data suggest that structural changes do occur on fragmentation but seem to be localized in the tiered-beta-sheet domain which contains Tyr-37.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004815:Epidermal Growth Factor / Q000302:isolation & purification / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D051379:Mice; D010446:Peptide Fragments / Q000302:isolation & purification; D010777:Photochemistry; D011487:Protein Conformation; D013363:Submandibular Gland; D014357:Trypsin / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D004815:Epidermal Growth Factor; D014357:Trypsin