title: Investigation by photochemically-induced dynamic nuclear polarization and nuclear Overhauser enhancement 1H-NMR of the interaction between beta-endorphin and phospholipid micelles.
abstract: The photochemically-induced dynamic nuclear polarization technique has been used to investigate the access of a photoexcited flavin dye to tyrosyl and histidyl residues in [Met]enkephalin and human and camel beta-endorphins, both alone and in the presence of n-dodecylphosphorylcholine micelles. The results indicate that the mode of binding of Tyr-1, but not of residue 27, is similar in the two endorphins and differs from that of Tyr-1 in [Met]enkephalin. In human beta-endorphin, accessibility and mobility of Tyr-27 are strongly reduced in the presence of lipid at physiological pH, whereas in camel beta-endorphin His-27 becomes immobilized only at high pH. Moreover, nuclear Overhauser enhancement experiments suggest a rigidifying influence of the peptide on the polar head groups of the micelles.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002162:Camelus; D003102:Colloids; D004723:Endorphins / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D010743:Phospholipids / Q000378:metabolism*; D010777:Photochemistry; D001615:beta-Endorphin
chemical_list: D003102:Colloids; D004723:Endorphins; D008823:Micelles; D010743:Phospholipids; D004744:Enkephalin, Methionine; D001615:beta-Endorphin