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N Ling

Publications and source records attributed to N Ling.

At least 415 records · Page 23Linked to original sources
PubMed1976

Isolation, primary structure, and synthesis of alpha-endorphin and gamma-endorphin, two peptides of hypothalamic-hypophysial origin with morphinomimetic activity.

The isolation and primary structure of two peptides with morphinomimetic activity, obtained from an extract of porcine hypothalamus-neurohypophysis, are described. The amino acid sequence of the two peptides, named alpha-endorphin and gamma-endophin, was determined by mass spectrometry and danxyl-Edman methods to be H-Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-OH and H-Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-Leu-OH, respectively. These correspond to the amino acid sequences present between residues 61 and 76 and residues 61 and 77 of the various beta-lipotropins. A third peptide also obtained in pure form in these studies was found to be an unstable salt of alpha-endorphin.

Amino Acid Sequence↗
PubMed1976

beta-Lipotropin as a prohormone for the morphinomimetic peptides endorphins and enkephalins.

The hypophysial homomeric peptide beta-lipotropin (beta-LPH-[1-91]) has no morphinomomimetic activity in a bioassay (myenteric plexus-longitudinal muscle of the guinea pig's ileum) or binding assays with stereospecific opiate-receptors of rat brain synaptosome preparations. Incubating beta-LPH-[1-91] at neutral pH with the supernatant aqueous extracts of rat brain generates (fragments of beta-LPH with) morphinomimetic activity in the same assay systems. These results are related to the recently recognized structural relationships between beta-LPH, the newly isolated peptides met-enkephalin (beta-LPH-[61-65]) and alpha-endorphin (beta-LPH-[61-76]) and also to the biologically active fragments of analogs: beta-LPH-[61-64], beta-LPH-[61-65[-NH2, (Met(O)65)-BETA-LPH-[61-65], beta-LPH-[61-69], and beta-LPH-[61-69]. Enzymatic biogenesis of these morphinomimetic peptides would preclude localizing them as such in cellular or subcellular elements with currently available methodology.

Amino Acid Sequence↗
PubMed1976

Morphinomimetic activity of synthetic fragments of beta-lipotropin and analogs.

In the myenteric plexus-longitudinal muscle bioassay, beta-endorphin, i.e., beta-lipotropin (beta-LPH)-[61-91], has a potency of 450 with confidence limits of 281-966 when Met5-enkephalin is used as a reference standard with a potency of 100. The primary amide and the ethylamide of Met5-enkephalin have potencies statistically overlapping with that of beta-endorphin. The primary amide of alpha-endorphin has twice the potency of the free acid form of alpha-endorphin. An intact NH2-terminal tyrosine is not necessary for full intrinsic activity. The shortest fragment of beta-LPH with morphinomimetic activity is beta-LPH-[61-64].

Amino Acid Sequence↗
PubMed1975

Somatostatin.

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Amino Acid Sequence↗
PubMed1975

Comparative study of proteins extracted form metal-induced allergic and foreign body granulomas in man.

In order to characterize proteins unique to organized epitheloid cells, proteins havebeen sequentially extracted form both foreign body and allergic granulomas in man at varoius times after intradermal injection of beryllium oxide suspension. Treitium-labeled l-tyrosine was injected intralesionally 2 weeks before excision of granulomas. Prolongedextraction with 8 m urea yeilded increases amounts of radioactivie protein form older (8-to 26-week) allergic granulomas but not from 4-to6-week-old or foreign body granulomas (consisting of mononuclear cells and phagocytes). Sephadex G-200 column chromatographyand sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of the urea extractsfrom 8-week and older allergic granulomas revealed distinct readioactive protein peaks with molecular weights of approximately 172,000 to 208,000. Antisera raised to one of these proteins gave a precipitin line in agar gel diffusion with lines of identity againsturea extracts of several allergic granulomas but not against similiar extracts of foreignbody granulomas. The results suggest synthesis of distinctive high molecular weight proteins in allergic granulomas which may serve as "markers" for organized epitheloid cell granulomas as they transform from mononuclear cells.

Animals↗