Synthesis and activities of neurotensin, and its acid and amide analogs: possible natural occurrence of [Gln4]-neurotensin.
It was considered, a priori, that the isolation of the tridecapeptide, neurotensin, might have inadvertently sllowed the hydrolysis of either the [Gln4]- or the [Leu13-NH2]-moieties. Neurotensin and its three acid and amide analogs, i.e., [Gln4]-neurotensin, neurotensin-NH2, and [Gln4]-neurotensin-NH2 were synthesized. Neurotensin and [Gln4]-neurotensin were indistinguishable by the hypotensive assay, hyperglycemic assay, contraction of the ileum, and radioimmunoassay. Neurotensin-NH2 and [Gln4]-neurotensin-NH2 showed less than 1% of these neurotensin activities. Present information does not elucidate whether the glutamic acid residue in position 4 of neurotensin in situ is present as Glu4 or as Gln4. At high levels, neurotensin released the luteinizing hormone, follicle stimulating hormone, and thyrotropin; [Gln4]-neurotensin-NH2 released thyrotropin, and [Gln4]-neurotensin released luteinizing hormone and follicle stimulating hormone, but these activities do not appear biologically significant.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D003429:Cross Reactions; D005973:Glutamine; D006065:Gonadotropins, Pituitary / Q000378:metabolism; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009419:Nerve Tissue Proteins / Q000138:chemical synthesis / Q000276:immunology / Q000494:pharmacology; D010455:Peptides / Q000138:chemical synthesis; D051381:Rats; D013329:Structure-Activity Relationship
D001786:Blood Glucose; D006065:Gonadotropins, Pituitary; D009419:Nerve Tissue Proteins; D010455:Peptides; D005973:Glutamine