Biomaterial Database

Structure-activity relationships of met5- and leu5-enkephalin analogues. 1979

M J Quinn, and F J Laska, and M R Fennessy

1. The effect of various analogues of met5- and leu5-enkephalin were determined on the reduction in twitch height of the electrically-stimulated longitudinal muscle preparation of the guinea-pig ileum and of the isolated mouse vas deferens. 2. In the guinea-pig ileum, D-alanine2-met5-enkephalin was the most potent whereas leu5-enkephalin was the most potent in the mouse vas deferens. 3. The met5-enkephalin analogues were more effective in reducing the twitch height of the ileum than they were in depressing that of the vas deferens preparation. The leu5-enkephalin analogues were more potent in their effects on the mouse vas deferens than they were on the guinea-pig ileum. 4. When a peptide bond is replaced by a glycol bond as in glycol2-3-leu5-enkephalin there is a marked reduction in opiate-like activity. 5. Substitution of a D-alanine residue for the glycine2 residue, as in D-alanine2-met5-enkephalin, increases the duration and potency of opiate-like activity. 6. These results confirm that modification of either met5- or leu5-enkephalin can alter the opiate-like potency of the resulting analogues. It appears that an intact tyrosyl residue of leu5-enkephalin is essential for such activity and that substitution of a D-alanine2 residue for the glycine2 residue confers resistance to enzymatic degradation on the met5-enkephalin peptide. In addition, the glycine2-3 peptide bond is essential for opiate-like activity.

UI	MeSH Term	Description	Entries
D007082	Ileum	The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.
D008297	Male		Males
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D004723	Endorphins	One of the three major groups of endogenous opioid peptides. They are large peptides derived from the PRO-OPIOMELANOCORTIN precursor. The known members of this group are alpha-, beta-, and gamma-endorphin. The term endorphin is also sometimes used to refer to all opioid peptides, but the narrower sense is used here; OPIOID PEPTIDES is used for the broader group.	Endorphin
D004745	Enkephalins	One of the three major families of endogenous opioid peptides. The enkephalins are pentapeptides that are widespread in the central and peripheral nervous systems and in the adrenal medulla.	Enkephalin
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor