des-(1-13) human beta-endorphin interacts with calmodulin |
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Authors: | D Puett D P Giedroc S Tollefson N Ling |
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Institution: | Department of Biochemistry, Vanderbilt University, Nashville, TN 37232 USA;The Neuroendocrinology Laboratory, The Salk Institute, La Jolla, CA 92037, USA |
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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. |
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Keywords: | Phosphodiesterase Circular dichroism |
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