title: des-(1-13) human beta-endorphin interacts with calmodulin.
abstract: It is known that the 31-residue neuropeptide beta-endorphin inhibits the calcium-dependent, calmodulin-mediated stimulation of cyclic nucleotide phosphodiesterase activity. The results of this study demonstrate that a non-opiate, synthetic amino terminal deletion peptide, des-(1-13), of human beta-endorphin is also capable of inhibiting the stimulated enzymic activity, but not the basal activity. This inhibition occurs with the same efficacy as the intact 31-residue peptide. Thus, the amino terminal region of beta-endorphin, which is responsible for opiate activity, does not appear to contribute to the calmodulin interaction. Circular dichroic spectroscopy of des-(1-13) beta-endorphin, calmodulin, and mixtures of the two shows that the ellipticity at 221 nm was more negative in the peptide-protein mixture than could be accounted for on the basis of simple additivity of the peptide and calmodulin. This spectral change implies enhanced alpha-helicity concomitant with the peptide-protein association. Helix formation may occur in the peptide since this sequence has the potential to form an amphipathic helix.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D002942:Circular Dichroism; D004723:Endorphins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D010446:Peptide Fragments / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D013552:Swine; D001615:beta-Endorphin
chemical_list: D002147:Calmodulin; D004723:Endorphins; D010446:Peptide Fragments; D001615:beta-Endorphin; C042418:beta-endorphin (13-31); D015105:3',5'-Cyclic-AMP Phosphodiesterases