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Query: UNIPROT:P01350 (gastrin)
 9,683 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our previous work on the effect of modification of peptide bonds in gastrin-like peptides led us to speculate that cleavage of the bond between the Met and Asp residues occurs in gastric mucosal membranes, and that this cleavage may have functional significance. In agreement with this speculation, we now show that the tetragastrin analogue BOC-Trp-Leu-Asp-Phe-NH2 (1) is degraded by a membrane fraction from rat gastric mucosa, and that the main products are BOC-Trp-Leu and Asp-Phe-NH2. Pseudo-peptide analogues in which the peptide bonds are replaced by CH2NH had differing stabilities; BOC-Trp-Leu-Asp-psi (CH2NH)-Phe NH2 (4) and BOC-Trp-Leu-psi(CH2NH)-Asp-Phe-NH2 (3) were stable under the incubation conditions, whereas BOC-Trp-psi(CH2NH)-Leu-Asp-Phe-NH2 (2) was degraded. The peptide and pseudo-peptide which were degraded (1 and 2) have been shown to stimulate gastric acid secretion in rats, in vivo, whereas 3 and 4 (which were not hydrolyzed) were inactive in stimulating gastric acid secretion and were found to antagonize the action of gastrin.
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PMID:Degradation of a tetragastrin analogue by a membrane fraction from rat gastric mucosa. 350 44

The effects of partial retro-inverso modifications of selected peptide bonds of the N-terminal tetrapeptide of gastrin have been studied. In some of the synthesized compounds, the phenylalanyl residue has been replaced by the (R,S)-2-benzylmalonyl, 3-phenylpropionyl, benzylcarbamoyl, or benzyloxycarbonyl moieties. All pseudopeptides showed affinity for the gastrin receptor, in vitro, with potencies varying from IC50 = 10(-7) to IC50 = 10(-4) M. These compounds exhibited little or no activity on acid secretion in the anesthetized rat but were able to antagonize the action of gastrin. Among the most potent were Boc-Trp-Leu-gAsp-CO-CH2CH2C6H5 (20) (ED50 = 0.15 microM/kg), Boc-Trp-Leu-gAsp-m(R,S)Phe-NH2 (3) (ED50 = 0.15 microM/kg), and Boc-Trp-gLeu-D-Asp-m(R,S)Phe-NH2 (7) (ED50 = 0.3 microM/kg).
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PMID:Synthesis and biological activity of partially modified retro-inverso pseudopeptide derivatives of the C-terminal tetrapeptide of gastrin. 357 63

Recently, glycine-extended processing intermediates of progastrin were identified in porcine stomach using a radioimmunoassay with conventional polyclonal antisera developed against a synthetic peptide analogue for progastrin processing intermediates, gastrin 6-G(Tyr-Gly-Trp-Met-Asp-Phe-Gly). We developed monoclonal antibodies specific for glycine-extended processing intermediates of progastrin (gastrin G). Monoclonal antibody 109-21 appeared to require the carboxyl-terminal pentapeptide structure of gastrin 6-G for maximal binding. Cross-reactivities of 109-21 against gastrin 17 I, gastrin 17 II, cholecystokinin-octapeptide, des(SO3) cholecystokinin-octapeptide, and gastrin 6-G-R-R were respectively 1%, less than 0.1%, less than 0.1%, 0.1%, and 0.5%. With this monoclonal antibody and a polyclonal gastrin antibody we examined the concentrations of gastrin and gastrin G in tissue and the effects of bombesin on the release of gastrin and gastrin G from rat antral mucosa in tissue culture. The gastrin G to gastrin ratio was 2.2 in rat antral mucosa and 0.66 in rat duodenal mucosa. In tissue culture, bombesin significantly stimulated gastrin and gastrin-G secretion at doses of 10(-8) and 3 X 10(-8) M. Atropine (10(-6) M) abolished the actions of carbachol to stimulate gastrin and gastrin-G secretion but had no effect on bombesin-stimulated gastrin and gastrin-G secretion. These results suggest that gastrin G is cosecreted with gastrin in response to carbachol and bombesin, and the stimulation of gastrin and gastrin-G secretion by bombesin does not involve cholinergic neural pathways and may reflect a direct action on gastrin cells.
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PMID:Effects of bombesin on the release of glycine-extended progastrin (gastrin G) in rat antral tissue culture. 359 69

The secondary structures of three gastrin analogs, HC1 X H-Trp-Nle-Asp(O-tBu)-Phe-NH2 (tetragastrin), pGlu-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH2 (octagastrin), and H-Leu-(Glu)5-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH2 (minigastrin) were studied by 1H-n.m.r. in dimethylsulfoxide and in trifluoroethanol. All three compounds were found to assume a random conformation in the former solvent, while some ordered secondary structure is present in trifluoroethanol even at the tetrapeptide level. This was shown by temperature studies and solvent titrations. At least four amide protons were found to be solvent shielded in the longer hormone.
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PMID:Conformational studies on gastrin related peptides by high resolution 1H-n.m.r. 369 83

Four analogues of Z-CCK-27-32-NH2, Z-Tyr(SO3-)-Met-Gly-Trp-Met-Asp-NH2, a cholecystokinin receptor antagonist have been synthesized by solution methodology. In these analogues, Z-Tyr(SO3-)-Nle-Gly-Trp-Met-Asp-NH2 16, Z-Tyr(SO3-)-Nle-Gly-Trp-Nle-Asp-NH2 17, BOC-Tyr(SO3-)-Met-Gly-Trp-Met-Asp-NH2 24 and Boc-Tyr(SO3-)-Met-Gly-Trp-Nle-Asp-NH2 25 methionyl residues were replaced by norleucyl residues. Preliminary biological activity on gastrin-induced acid secretion, in rat, are reported. These derivatives proved to antagonize the action of gastrin, with ED 50 of between 0.5 and 3 mg/kg.
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PMID:Synthesis of analogues of the Des-Phe-NH2 C-terminal hexapeptide of cholecystokinin showing gastrin antagonist activity. 371 Jun 94

A peptide that cross-reacted with C-terminal gastrin/CCK antisera was isolated from chicken antral extracts by a combination of gel filtration and reversed-phase HPLC. The sequence was: Phe-Leu-Pro-His- Val-Phe-Ala-Glu-Leu-Ser-Asp-Arg-Lys-Gly-Phe-Val-Gln-Gly-Asn-Gly-Ala- Val-Glu-Ala-Leu-His-Asp-His-Phe-Tyr-Pro-Asp-Trp-Met-Asp-Phe(NH2). Aside from the C-terminal tetrapeptide and the Tyr residue, the molecule does not resemble other known forms of gastrin or CCK. The peptide was a potent stimulus of avian gastric acid but not pancreatic secretion. The results have important implications for the structure-activity and evolutionary relationships of the gastrin/CCK family.
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PMID:Isolation from chicken antrum, and primary amino acid sequence of a novel 36-residue peptide of the gastrin/CCK family. 374 81

A sulfated, myotropic neuropeptide termed leucosulfakinin (Glu-Gln-Phe-Glu-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2) was isolated from head extracts of the cockroach Leucophaea maderae. The peptide exhibits sequence homology with the hormonally active portion of the vertebrate hormones human gastrin II and cholecystokinin, suggesting that these peptides are evolutionarily related. Six of the 11 amino acid residues (55 percent) are identical to those in gastrin II. In addition, the intestinal myotropic action of leucosulfakinin is analogous to that of gastrin.
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PMID:Leucosulfakinin, a sulfated insect neuropeptide with homology to gastrin and cholecystokinin. 374 93

A sulfated neuropeptide [pGlu-Ser-Asp-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2], with a blocked N-terminus and related to the undecapeptide leucosulfakinin, has been isolated from head extracts of the cockroach, Leucophaea maderae. It exhibits sequence homology with the hormonally-active portion of vertebrate hormones cholecystokinin, human gastrin II and caerulin. This peptide, termed leucosulfakinin-II, shares a common C-terminal heptapeptide fragment with leucosulfakinin and a comparison of the two sequences provides an assessment of the importance of the constituent amino acids to biological activity. Leucosulfakinin-II shows a greater resemblance to cholecystokinin than does leucosulfakinin. Leucosulfakinin-II and leucosulfakinin are the only two reported invertebrate sulfated neuropeptides. As with leucosulfakinin, the intestinal myotropic activity of leucosulfakinin-II is analogous to that of gastrin and cholecystokinin. The sequence homology between the leucosulfakinins and the vertebrate hormones, as well as their analogous myotropic activity, suggest that gastrin/cholecystokinin-like neuropeptides are not confined to vertebrates, but also occur in invertebrates.
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PMID:Leucosulfakinin-II, a blocked sulfated insect neuropeptide with homology to cholecystokinin and gastrin. 377 55

A series of phenethyl ester derivative analogues of the C-terminal tetrapeptide of gastrin, in which the phenylalanyl residue has been replaced by a phenethyl group and the peptide bond between aspartic acid and phenylalanine by an ester bond, were synthesized. None of these derivatives were able to stimulate gastric acid secretion in the anesthetized rat, whereas they inhibited gastrin-induced acid secretion with ED50 values between 0.02 and 1.5 mg/kg. Among these derivatives, Boc-beta Ala-Trp-Leu-Asp phenethyl ester (9) and Boc-beta Ala-Trp-Leu-Asp p-fluorophenethyl ester (16) were very potent in inhibiting gastrin-induced acid secretion. From these studies, the significant role of the C-terminal dipeptide of gastrin was pointed out. More particularly, the functional role of the phenylalanine through the C-terminal carboxamide and its binding role through its aromatic ring were demonstrated.
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PMID:Phenethyl ester derivative analogues of the C-terminal tetrapeptide of gastrin as potent gastrin antagonists. 378 82

Boc-Trp-Met-Asp-NH2 was described as the smallest peptidic fragment which presented gastric antisecretory activity. Some pharmacological aspects of a peptide analogue, Boc-Trp-Leu-Asp-NH2 (Boc-WLD-NH2), were studied on the main biological functions of gastrin. This compound was found to inhibit the binding of gastrin to isolated gastric fundic mucosal cells (IC50 50 microM). On pentagastrin-induced gastric acid secretion in the rat, a dose-dependent inhibition was observed with an ID50 of 55 mumol/kg when pentagastrin (1 microgram/kg per h) was continuously infused and with an ID50 of 7.8 mumol/kg when pentagastrin (1 microgram/kg) was bolus i.v. injected. Similar inhibition was observed on acid secretion induced by pentagastrin in the isolated rat gastric mucosa (IC50 100 microM), whereas the tripeptide had no effect when acid output was triggered by histamine. A dose-dependent inhibition with the tripeptide was shown on pentagastrin induced guinea-pig ileum contractions (IC50 31 microM). The compound had no activity on histamine-stimulated guinea-pig atria (histamine H2-receptor). These results suggest some evidence for a selective antigastrin activity.
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PMID:Pharmacological profile of a new peptidic gastrin antagonist. 378 33


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