Biochemical characterization of high-affinity 3H-opioid binding. Further evidence for Mu1 sites

Journal Article · Sat Dec 31 23:00:00 EST 1983 · Mol. Pharmacol.; (United States)

OSTI ID:6975617

Nishimura, S L; Recht, L D; Pasternak, G W

In saturation studies with (/sup 3/H)dihydromorphine, unlabeled D-Ala2-D-Leu5-enkephalin (1 nM) inhibited the high-affinity binding component far more potently than the lower-affinity one. Similarly, morphine (1 nM) inhibited the higher-affinity binding of /sup 3/H-D-Ala2-D-Leu5-enkephalin to a greater extent than its lower-affinity binding component, consistent with a common high-affinity binding site for opiates and enkephalins. Treatment of tissue with either trypsin (1 microgram/ml) or N-ethylmaleimide (25 microM) effectively eliminated the high-affinity binding component of a series of /sup 3/H-opiates and opioid peptides. Competition studies following both treatments were consistent with a common high-affinity binding site. Both treatments also eliminated the ability of low morphine concentrations (less than 1 nM) to inhibit /sup 3/H-D-Ala2-D-Leu5-enkephalin binding and of low D-Ala2-D-Leu5-enkephalin concentrations (less than 1 nM) to inhibit (/sup 3/H)dihydromorphine binding. Protection experiments examining N-ethylmaleimide (25 microM) inhibition of (/sup 3/H)dihydromorphine binding showed significant protection (p less than 0.002) by both unlabeled D-Ala2-D-Leu5-enkephalin and morphine (both at 1 nM). When studied together, both naloxonazine and N-ethylmaleimide inhibited (/sup 3/H)dihydromorphine binding to a similar extent. Equally important, tissue previously treated with naloxonazine was far less sensitive to N-ethylmaleimide than was untreated control tissue, consistent with the possibility that both treatments affected the same site. Together, these results support the concept of a common high-affinity binding site for opiates and opioid peptides.

• Research Organization: Cotzias Laboratory of Neuro-Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York
• OSTI ID: 6975617
• Journal Information: Mol. Pharmacol.; (United States), Journal Name: Mol. Pharmacol.; (United States) Vol. 25:1; ISSN MOPMA
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
ALKALOIDS
ANALGESICS
ANIMALS
BIOCHEMICAL REACTION KINETICS
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM DEPRESSANTS
DRUGS
ENZYMES
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANES
MORPHINE
NARCOTICS
OPIUM
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SERINE PROTEINASES
STRUCTURE-ACTIVITY RELATIONSHIPS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
TRYPSIN
VERTEBRATES