THE DEVELOPMENT OF PEPTIDE MODELS OF B-ENDORPHIN

Project Details

Description

The approach of studying peptide models of Beta-endorphin that have minimal
homology to natural sequences will be used to determine the conformation
requirements of peptides for binding to different opiate receptors and
eliciting a biological response. A model peptide will be prepared that
consists of the [Met5]-enkephalin structure connected to a model
amphiphilic Alpha-helical domain consisting of leucine, lysine and
glutamine residues via a linking peptide composed of alternating serine and
glycine residues. This peptide will be obtained by expression of a
chemically synthesized gene coding for a chimeric protein specifically
designed to form a stable tertiary structure of which the Beta-endorphin
model peptide is an integral part. After purification, the Beta-endorphin
model peptide will be enzymatically cleaved from this protein and tested
for binding to radiolabelled Delta- and Mu-opiate receptors, opiate
activity on the rat vas deferens and analgesic activity upon intracerebral
injection of mice. A series of peptides having single and multiple amino
acid residue changes from this model peptide will then be prepared by
oligonucleotide-directed mutagenesis of the synthetic gene in order to test
(1) the length requirements of the hydrophilic linking peptide, (2) the
importance of specific features of the hydrophobic domain of the
amphiphilic Alpha-helical structure, and (3) the effect of destabilizing
the amphiphilic Alpha-helical structure. The rapid development of peptides
consisting of naturally-occurring amino acid residues that combine a high
selectivity for opiate receptor subtypes with a long biological half life
and rapid diffusion to their sites of action should then be possible. In
addition, by determining the factors affecting binding affinity versus
efficacy, peptide antagonists of selected opiate receptor subtypes might
also be developed. Such peptides will have potential clinical uses as
analgetics that minimize undesirable side effects, as well as providing
pharmacological tools useful in understanding the actions of the opioid
peptides in general. The modelling approach used combined with the
development of a rational design for chimeric proteins should elucidate
fundamental principles of peptide hormone structure-function relationships,
protein folding and tertiary structure that will be applicable to other
systems.
StatusFinished
Effective start/end date12/31/898/31/98

Funding

  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse
  • National Institute on Drug Abuse

ASJC

  • Medicine(all)
  • Chemical Engineering(all)
  • Structural Biology
  • Biochemistry
  • Pharmacology

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