In vitrometabolism of an insect neuropeptide by homogenates of the nematodeCaenorhabditis elegans

2003 ◽  
Vol 77 (1) ◽  
pp. 43-48 ◽  
Author(s):  
E.P. Masler
Keyword(s):  
General Pattern ◽  
Residue Analysis ◽  
Aminopeptidase Activity ◽  
Soil Nematode ◽  
Peptide Fragments ◽  
Adipokinetic Hormone ◽  
Initial Product ◽  
Insect Neuropeptide ◽  
Endoproteolytic Cleavage ◽  
N Terminus

AbstractThe cytosolic fraction of homogenates from the free-living soil nematodeCaenorhabditis elegansis capable of metabolizing the insect neuropeptide adipokinetic hormone, a decapeptide blocked at the N-terminus by a pGlu residue. Analysis of digests by RP-HPLC and LC-MS revealed that an initial endoproteolytic cleavage step produced a heptapeptide with an unblocked N-terminus that can serve as a substrate for aminopeptidases. The aminopeptidase activity is depressed in the presence of the inhibitor amastatin; the initial product of the endoproteolytic step accumulates during incubation, and expected aminopeptidase product peptides are reduced in amount, as assessed by chromatographic peak size. The absence of some expected peptide fragments in the reaction mixtures suggests that multiple proteases contribute to short peptide half-lives. Comparison of the adipokinetic hormone digestion inC. elegansto that reported previously for insects reveals the same general pattern of peptide fragment production.

scholarly journals Copper(II) Coordination Abilities of the Tau Protein's N‐Terminus Peptide Fragments: A Combined Potentiometric, Spectroscopic and Mass Spectrometric Study

ChemPlusChem ◽  
2019 ◽  
Vol 84 (11) ◽  
pp. 1697-1708 ◽  
Author(s):  
Márton Lukács ◽  
Györgyi Szunyog ◽  
Ágnes Grenács ◽  
Norbert Lihi ◽  
Csilla Kállay ◽  
...  
Keyword(s):  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
Peptide Fragments ◽  
N Terminus

Phosphopeptides from Grana Padano cheese: nature, origin and changes during ripening

1997 ◽  
Vol 64 (4) ◽  
pp. 601-615 ◽  
Author(s):  
PASQUALE FERRANTI ◽  
FRANCESCA BARONE ◽  
LINA CHIANESE ◽  
FRANCESCO ADDEO ◽  
ANDREA SCALONI ◽  
...  
Keyword(s):  
Fast Atom Bombardment ◽  
Aminopeptidase Activity ◽  
Edman Degradation ◽  
Cheese Sample ◽  
Cheese Ripening ◽  
Casein Phosphopeptides ◽  
N Terminus ◽  
Hplc Profiles ◽  
Grana Padano ◽  
Grana Padano Cheese

Casein phosphopeptides (CPP) which develop in Grana Padano cheese at different ages were isolated by precipitation with Ba2+ and analysed by HPLC. Profiles were complex throughout the period between 4 and 38 months. CPP in a cheese sample 14 months old were identified by a combination of fast atom bombardment–mass spectrometry and Edman degradation. They were found to consist of a mixture of components derived from three parent peptides, β-CNf(7–28)4P, αs1-CNf(61–79)4P and αs1-CNf(7–21)4P. In total, 45 phosphopeptides were identified: 24 from β-CN, 16 from αs1-CN and 5 from αs2-CN. The presence of aminopeptidase activity during cheese ripening was deduced from the presence of a number of CPP of different lengths with the loss of one or more residues from the N-terminus. The longest had C-terminal lysine and seemed to be progressively hydrolysed by carboxypeptidases A and B to shorter peptides. CPP in cheese appeared to be shortened plasmin-mediated products. Moreover, those most resistant to further hydrolysis contained at least three closely located phosphoserine residues. The anticariogenic activity of CPP is also discussed.

scholarly journals Discovery of a Novel Insect Neuropeptide Signaling System Closely Related to the Insect Adipokinetic Hormone and Corazonin Hormonal Systems

2010 ◽  
Vol 285 (14) ◽  
pp. 10736-10747 ◽  
Author(s):  
Karina K. Hansen ◽  
Elisabeth Stafflinger ◽  
Martina Schneider ◽  
Frank Hauser ◽  
Giuseppe Cazzamali ◽  
...  
Keyword(s):  
Signaling System ◽  
Adipokinetic Hormone ◽  
Insect Neuropeptide

scholarly journals Electron-Based Dissociation Is Needed for O-Glycopeptides Derived from OpeRATOR Proteolysis

2020 ◽  
Author(s):  
Nicholas Riley ◽  
Stacy Malaker ◽  
Carolyn Bertozzi
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Tandem Mass ◽  
Peptide Fragments ◽  
Terminal Residue ◽  
Bacterial Enzyme ◽  
N Terminus ◽  
Modified Peptides ◽  
Potential Benefits

<p>The recently described O-glycoprotease OpeRATOR presents exciting opportunities for O-glycoproteomics. This bacterial enzyme purified from <i>Akkermansia (Sp). muciniphila</i> cleaves N-terminally to serine and threonine residues that are modified with (preferably asialylated) O-glycans. This <a>provides orthogonal cleavage relative to canonical proteases (e.g., trypsin) for improved O-glycopeptide characterization with tandem mass spectrometry (MS/MS). O-glycopeptides with a modified N-terminal residue, such as those generated by OpeRATOR, present several potential benefits, perhaps the most notable being <i>de facto</i> O-glycosite localization without the need of glycan-retaining fragments in MS/MS spectra. Indeed, O-glycopeptides modified exclusively at the N-terminus would enable O-glycoproteomic methods to rely solely on collision-based fragmentation rather than electron-driven dissociation because glycan-retaining peptide fragments would not be required for localization. The caveat is that modified peptides would need to reliably contain only a single O-glycosite. </a>Here we use methods that combine collision- and electron-based fragmentation to characterize the number of <i>O-</i>glycosites that are present in <i>O-</i>glycopeptides derived from OpeRATOR digestion of four known <i>O-</i>glycoproteins. Our data show that over 50% of <i>O-</i>glycopeptides generated from combined digestion using OpeRATOR and trypsin contain multiple <i>O-</i>glycosites, indicating that collision-based fragmentation alone is not sufficient. Electron-based dissociation methods are necessary to capture the <i>O-</i>glycopeptide diversity present in OpeRATOR digestions. </p>

scholarly journals Preparation and Use of a General Solid-Phase Intermediate to Biomimetic Scaffolds and Peptide Condensations

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1762
Author(s):  
J. Samaritoni ◽  
Jacek Martynow ◽  
Martin O’Donnell ◽  
William Scott
Keyword(s):  
Functional Groups ◽  
Solid Phase ◽  
Neglected Diseases ◽  
Synthetic Route ◽  
Peptide Fragments ◽  
Peptide Chemistry ◽  
Large Numbers ◽  
Biomimetic Scaffolds ◽  
N Terminus ◽  
Variable Substitution

The Distributed Drug Discovery (D3) program develops simple, powerful, and reproducible procedures to enable the distributed synthesis of large numbers of potential drugs for neglected diseases. The synthetic protocols are solid-phase based and inspired by published work. One promising article reported that many biomimetic molecules based on diverse scaffolds with three or more sites of variable substitution can be synthesized in one or two steps from a common key aldehyde intermediate. This intermediate was prepared by the ozonolysis of a precursor functionalized at two variable sites, restricting their presence in the subsequently formed scaffolds to ozone compatible functional groups. To broaden the scope of the groups available at one of these variable sites, we developed a synthetic route to an alternative, orthogonally protected key intermediate that allows the incorporation of ozone sensitive groups after the ozonolysis step. The utility of this orthogonally protected intermediate is demonstrated in the synthesis of several representative biomimetic scaffolds containing ozonolytically labile functional groups. It is compatible with traditional Fmoc peptide chemistry, permitting it to incorporate peptide fragments for use in fragment condensations with peptides containing cysteine at the N-terminus. Overall yields for its synthesis and utilization (as many as 13 steps) indicate good conversions at each step.

scholarly journals The stimulation of glycogenolysis in isolated hepatocytes by opioid peptides

1985 ◽  
Vol 227 (1) ◽  
pp. 191-197 ◽  
Author(s):  
R P Leach ◽  
E H Allan ◽  
M A Titheradge
Keyword(s):  
Opioid Peptides ◽  
Isolated Hepatocytes ◽  
Aminopeptidase Activity ◽  
Initial Product ◽  
Transient Nature ◽  
Adrenergic Antagonists ◽  
Lactate Formation ◽  
Glucose Output ◽  
Dependent Mechanism ◽  
Stimulation Of

Addition of the opioid peptides, [Leu]enkephalin and [Met]enkephalin, to isolated hepatocytes was shown to produce a stimulation of glycogenolysis comparable with that observed in the presence of maximal concentrations of glucagon, adrenaline or angiotensin. This stimulation was demonstrated to be the result of an activation of phosphorylase by a rapid Ca2+-dependent mechanism and was not decreased by the presence or either alpha- or beta-adrenergic antagonists, although it was dependent on the presence of the N-terminal tyrosine residue in the enkephalin molecule. It is suggested that this may be further evidence for specific opioid receptors in the liver. Addition of [Leu]enkephalin also inhibited lactate formation, indicating that the opioid peptides exert a concerted effect on hepatic carbohydrate metabolism to enhance glucose output. The transient nature of the effect of the enkephalins was shown to be the result of a rapid breakdown of the peptides in the incubation as a result of aminopeptidase activity, the initial product being the inactive des-tyrosine derivative.

scholarly journals Neuropeptide-degrading endopeptidase activity of locust (Schistocerca gregaria) synaptic membranes

1988 ◽  
Vol 255 (3) ◽  
pp. 843-847 ◽  
Author(s):  
R E Isaac
Keyword(s):  
Schistocerca Gregaria ◽  
Physiological Role ◽  
Aminopeptidase Activity ◽  
Synaptic Membranes ◽  
Synaptic Membrane ◽  
Adipokinetic Hormone ◽  
Peptide Bonds ◽  
Endopeptidase 24.11 ◽  
Endopeptidase Activity ◽  
Neural Membranes

Locust adipokinetic hormone (AKH, pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2) was used as the substrate to measure neuropeptide-degrading endopeptidase activity in neutral membranes from ganglia of the locust Schistocerca gregaria. Initial hydrolysis of AKH at neural pH by peptidases of washed neural membranes generated pGlu-Leu-Asn and Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2 as primary metabolites, demonstrating that degradation was initiated by cleavage of the Asn-Phe bond. Amastatin protected the C-terminal fragment from further metabolism by aminopeptidase activity without inhibiting AKH degradation. The same fragments were generated on incubation of AKH with purified pig kidney endopeptidase 24.11, and enzyme known to cleave peptide bonds that involve the amino group of hydrophobic amino acids. Phosphoramidon (10 microM), a selective inhibitor of mammalian endopeptidase 24.11, partially inhibited the endopeptidase activity of locust neural membranes. This phosphoramidon-sensitive activity was shown to enriched in a synaptic membrane preparation with around 80% of the activity being inhibited by 10 microM-phosphoramidon (IC50 = 0.2 microM). The synaptic endopeptidase was also inhibited by 1 mM-EDTA, 1 mM-1,10-phenanthroline and 1 microM-thiorphan, and the activity was maximal between pH 7.3 and 8.0. Localization of the phosphoramidon-sensitive enzyme in synaptic membranes is consistent with a physiological role for this endopeptidase in the metabolism of insect peptides at the synapse.

scholarly journals Electron-Based Dissociation Is Needed for O-Glycopeptides Derived from OpeRATOR Proteolysis

2020 ◽  
Author(s):  
Nicholas Riley ◽  
Stacy Malaker ◽  
Carolyn Bertozzi
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Tandem Mass ◽  
Peptide Fragments ◽  
Terminal Residue ◽  
Bacterial Enzyme ◽  
N Terminus ◽  
Modified Peptides ◽  
Potential Benefits

<p>The recently described O-glycoprotease OpeRATOR presents exciting opportunities for O-glycoproteomics. This bacterial enzyme purified from <i>Akkermansia (Sp). muciniphila</i> cleaves N-terminally to serine and threonine residues that are modified with (preferably asialylated) O-glycans. This <a>provides orthogonal cleavage relative to canonical proteases (e.g., trypsin) for improved O-glycopeptide characterization with tandem mass spectrometry (MS/MS). O-glycopeptides with a modified N-terminal residue, such as those generated by OpeRATOR, present several potential benefits, perhaps the most notable being <i>de facto</i> O-glycosite localization without the need of glycan-retaining fragments in MS/MS spectra. Indeed, O-glycopeptides modified exclusively at the N-terminus would enable O-glycoproteomic methods to rely solely on collision-based fragmentation rather than electron-driven dissociation because glycan-retaining peptide fragments would not be required for localization. The caveat is that modified peptides would need to reliably contain only a single O-glycosite. </a>Here we use methods that combine collision- and electron-based fragmentation to characterize the number of <i>O-</i>glycosites that are present in <i>O-</i>glycopeptides derived from OpeRATOR digestion of four known <i>O-</i>glycoproteins. Our data show that over 50% of <i>O-</i>glycopeptides generated from combined digestion using OpeRATOR and trypsin contain multiple <i>O-</i>glycosites, indicating that collision-based fragmentation alone is not sufficient. Electron-based dissociation methods are necessary to capture the <i>O-</i>glycopeptide diversity present in OpeRATOR digestions. </p>

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