Identification of two related pentapeptides from the brain with potent opiate agonist activity

Hughes, J.; Smith, T.; Kosterlitz, H. W.; Fothergill, Linda A.; Morgan, Barry A.; Morris, Howard R.

doi:10.1038/258577a0

Cited by 3,634 publications

(957 citation statements)

References 16 publications

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“…Met-and Leu-enkephalin first isolated from pig brain as endogenous ligands for opioid receptors [1 ], have later been shown to occur also in peripheral nervous tissue such as the plexus of the gastrointestinal tract of some species [2] and the bovine adrenal medulla [3,4]. Peptides probably identical with Metand Leu-enkephalin are also present in neuroblastoma X glioma hybrid cells 108CC15, as determined by 3 independent assays [5,6].…”

Section: Introductionmentioning

confidence: 99%

Glucocorticoids elevate the level of enkephalin‐like peptides in neuroblastoma × glioma hybrid cells

Gläser¹,

Hübner²,

Hamprecht³

1981

FEBS Letters

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Section: Introductionmentioning

confidence: 99%

Glucocorticoids elevate the level of enkephalin‐like peptides in neuroblastoma × glioma hybrid cells

Gläser¹,

Hübner²,

Hamprecht³

1981

FEBS Letters

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“…In the literature, three fundamental 3D conformations have been characterized on these two endogenous opioid peptides using a variety of different methods°such°as°FT-IR°and°NMR°spectroscopy° [21,°22], molecular°modeling° [23][24][25],°and°mass°spectrometry [26,°27].°The°first°conformation°was°the°extended°con-formation, which can be stabilized by intermolecular hydrogen bonds. The second conformation is the ␤-turn folded form with two intramolecular hydrogen bonds; the°first°between°C¢O°(Tyr° [1]°and°N-H°(Gly° [3] and°the°second°between°C¢O°(Phe° [4]°and°N-H°(Tyr° [1]. The last conformation is the 3 10 -helix structure with an H°bond°between°C°ϭ°O°(Tyr° [1]°and°N-H°(Gly° [3]° [21, 28,°29].°These°conformations°have°been°characterized°in aqueous solutions, DMSO, and a mixture of these two solvents° [21].°Since°DMSO°has°a°similar°polarity°(P)°as acetonitrile (P ϭ 0.65 E°Al 2 O 3 for acetonitrile and P ϭ 0.62 E°Al 2 O 3 for DMSO), the resulting conformations are comparable with those characterized in the previous conditions.…”

Section: Molecular Modelingmentioning

confidence: 99%

“…The second conformation is the ␤-turn folded form with two intramolecular hydrogen bonds; the°first°between°C¢O°(Tyr° [1]°and°N-H°(Gly° [3] and°the°second°between°C¢O°(Phe° [4]°and°N-H°(Tyr° [1]. The last conformation is the 3 10 -helix structure with an H°bond°between°C°ϭ°O°(Tyr° [1]°and°N-H°(Gly° [3]° [21, 28,°29].°These°conformations°have°been°characterized°in aqueous solutions, DMSO, and a mixture of these two solvents° [21].°Since°DMSO°has°a°similar°polarity°(P)°as acetonitrile (P ϭ 0.65 E°Al 2 O 3 for acetonitrile and P ϭ 0.62 E°Al 2 O 3 for DMSO), the resulting conformations are comparable with those characterized in the previous conditions. In each case, the N-terminal function of these peptides is not involved in the hydrogen bonds; this observation leads us to suggest that the N primary labeling peptides would not dramatically influence conformations of the enkephalins.…”

Section: Molecular Modelingmentioning

confidence: 99%

Reaction of naphthalene-2,3-dicarboxaldehyde with enkephalins for LC-fluorescence and lc-ms analysis: Conformational studies by molecular modeling and H/D Exchange mass spectrometry

Lacroix

Garrigues

Couderc

2007

J. Am. Soc. Mass Spectrom.

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A new labeling method compatible with both laser-induced fluorescence (LIF) and MS detection for enkephalins, which uses naphthalene-2,3-dicarboxaldehyde (NDA) and a new nucleophilic agent (N,N-dimethylaminoethanethiol) is described. When the derivative is separated via reverse phase HPLC and detected via MS, two different peaks with similar exact mass but different fluorescence and fragmentation properties are obtained. To interpret these results, molecular modeling and H/D exchange mass spectrometry studies were investigated to test the hypothesis that the peak obtained by LC/LIF/MS analysis depends on the site of protonation of the labeled enkephalins. The peptides labeled with NDA and N,Ndimethylaminoethanethiol were separated on a reverse phase C18 column with a gradient of aqueous 0.1% formic acid and acetonitrile. In mass spectrometry, two peaks are observed with the same exact mass for each molecule while only one peak is detected using fluorescence. Tandem mass spectrometry experiments of ion m/z 809.5 were performed on each chromatographic peak; the first peak (which is not observed by LIF detection) gives a fragment corresponding to the loss of the aminothiol side chain while no fragmentation is observed on the second peak, which was detected by fluorescence. The hypothesis is that each peak represents the labeled enkephalin with different sites of protonation. According to this hypothesis, three fundamental conformations that were closed to the unlabeled leucine-enkephalin were obtained by molecular modeling: a ␤-turn like conformation with two hydrogen bonds, a 3 10 -helix with an H bond, and finally, the extended form without any intramolecular interactions. H/D exchange mass spectrometry experiments with D 2 O and d 2-formic acid as eluent was used to determine which conformation is involved in each peak. Hughes et al. in 1975 [1] with analgesic properties similar to that of morphine. The two enkephalins, leucine enkephalin (Leu-Enk) and methionine-enkephalin (Met-Enk) are pentapeptides, which differ at the C-terminal function (Tyr-Gly-Gly-Phe-Leu or Met) and act as neurotransmitters and neuromodulators [2]. These compounds exert a profound influence on many physiological and pathological states such as pain transmission, addiction, and dementia [2][3][4]. Opioid peptide levels are typically measured by radioimmunoassay (RIA), enzyme-linked immunoassay (ELISA), or radioreceptorassay (RRA) [5,6]. However, these modes of quantitation require a large sample volume and are reported to be less sensitive than chromatographic methods coupled with electrochemical detection [7]. The two most common methods for quantitation are capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) [8] coupled to electrochemical detectors [7], UV detectors [9], laser-induced fluorescence (LIF) detectors [10], or mass spectrometry detection [11,12].Stobaugh et al. have developed chromatographic methods to monitor leucine-enkephalin in biological samples using fluorescence detection. These workers ...

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“…15 This endogenous opioid pentapeptide was first discovered in the brain in the 1970s. 18,19 Investigations of structure-activity relationships showed that the Tyr 1 residue, the Phe 4 residue, and the Nterminal amino group are important for the opioid activity, and that the Gly at position 2 could be substituted with a D-amino acid 21 (for a review, see Ref. 20).…”

Section: Figurementioning

confidence: 99%

Parallel synthesis and biological evaluation of different sizes of bicyclo^[2,3]‐Leu‐enkephalin analogues

Gu¹,

Ying²,

Min³

et al. 2005

Biopolymers

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Identification of two related pentapeptides from the brain with potent opiate agonist activity

Cited by 3,634 publications

References 16 publications

Glucocorticoids elevate the level of enkephalin‐like peptides in neuroblastoma × glioma hybrid cells

Glucocorticoids elevate the level of enkephalin‐like peptides in neuroblastoma × glioma hybrid cells

Reaction of naphthalene-2,3-dicarboxaldehyde with enkephalins for LC-fluorescence and lc-ms analysis: Conformational studies by molecular modeling and H/D Exchange mass spectrometry

Parallel synthesis and biological evaluation of different sizes of bicyclo^[2,3]‐Leu‐enkephalin analogues

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Identification of two related pentapeptides from the brain with potent opiate agonist activity

Cited by 3,634 publications

References 16 publications

Glucocorticoids elevate the level of enkephalin‐like peptides in neuroblastoma × glioma hybrid cells

Glucocorticoids elevate the level of enkephalin‐like peptides in neuroblastoma × glioma hybrid cells

Reaction of naphthalene-2,3-dicarboxaldehyde with enkephalins for LC-fluorescence and lc-ms analysis: Conformational studies by molecular modeling and H/D Exchange mass spectrometry

Parallel synthesis and biological evaluation of different sizes of bicyclo[2,3]‐Leu‐enkephalin analogues

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Parallel synthesis and biological evaluation of different sizes of bicyclo^[2,3]‐Leu‐enkephalin analogues