Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using a radioimmunoassay specific for porcine glicentin C-terminal hexapeptide, we isolated a peptide from porcine pancreas and characterized it as the C-terminal 64-69 sequence of glicentin: H-Asn-Lys-Asn-Asn-Ile-Ala-OH. The purification steps included gel filtration, ion-exchange chromatography and HPLC. In each step, the recovery of the desired peptide, radioimmunologically estimated from the respective elution profile, was 71.4-91.7%. The final yield of the hexapeptide was 22 micrograms (4.3%) from 800 g pancreas. The pancreatic content of this peptide was estimated to be approximately equimolar to that of pancreatic glucagon. No hexapeptide-like component was detected in porcine intestinal extracts. The data confirmed that the processing of pancreatic proglucagon liberates the C-terminal hexapeptide of the intramolecular glicentin sequence in a tissue-specific manner during the production of glucagon.
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PMID:Isolation and chemical characterization of glicentin C-terminal hexapeptide in porcine pancreas. 402 98

The synthesis of Lys-Arg-Asn-Lys-Asn-Asn-Ile-Ala representing the C-terminal octapeptide of oxyntomodulin isolated from pig intestine is described. Its structure was confirmed by its 360-MHz 1H NMR spectra. The octapeptide was tested for its ability to inhibit pentagastrin-induced acid secretion, in the anaesthetized rat, in the conscious rat with chronic gastric fistula, and in the conscious cat with gastric chronic fistula. The octapeptide inhibits pentagastrin-induced acid secretion in all three models. Compared to oxyntomodulin, the parent hormone, the synthetic peptide was approximately 150 times less potent but has the same efficacy. Biological data are presented and discussed.
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PMID:Synthesis of the C-terminal octapeptide of pig oxyntomodulin. Lys-Arg-Asn-Lys-Asn-Asn-Ile-Ala: a potent inhibitor of pentagastrin-induced acid secretion. 404 27

Two glucagon-like peptides have been isolated from guinea pig pancreas and their primary structures determined. A 29-residue peptide is identical to the glucagons from all other mammals yet studied in the N-terminal region (residues 1-20) but the C-terminal region [Gln-Phe-Leu-Lys-Trp-Leu-Leu-Asn-Val] contains five substitutions. A 37-residue peptide probably represents guinea pig glucagon extended from the C-terminus by [Lys-Arg-Asn-Arg-Asn-Asn-Ile-Ala] and is analogous to human oxyntomodulin (glucagon-37). The structures suggest evolutionary pressure to conserve the N-terminal region of glucagon and the C-terminal region of oxyntomodulin. The biological activity of guinea pig glucagon has not yet been determined but it is speculated that changes in the C-terminal region of glucagon may have produced a molecule with reduced biological potency that is appropriate to the reduced potency of guinea pig insulin.
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PMID:Primary structure of glucagon and a partial sequence of oxyntomodulin (glucagon-37) from the guinea pig. 404 53

Ostrich serum albumin (OsSA) was purified by a combination of heat fractionation and polyethylene glycol precipitation. Equilibrium centrifugation revealed a relative molecular mass of 71,666 for the purified monomer, whereas the presence of a dimeric form was confirmed by means of PAGE and SDS-PAGE analysis. Compared to other species, relatively high levels of proline, glycine, isoleucine and histidine together with lowered amounts of half cystine, phenylalanine and arginine were observed in OsSA. A single N-terminal aspartic acid was identified. Isolated chicken adipocytes revealed a significantly lower in vitro lipolytic responsiveness towards added glucagon when OsSA replaced bovine serum albumin (BSA) in the medium (Km = 6.359 and 1.135 nM, Vm = 36.70 and 46.72 nmol/hr/micrograms adipocyte DNA for OsSA and BSA respectively).
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PMID:The isolation and characterization of serum albumin from the ostrich (Struthio camelus). 409 40

The administration of glucagon to rats causes a marked increase in the phosphorylation of a specific serine residue in lysine-rich (f1) histone of liver during a one-hour period following the administration of the hormone. It is proposed that histone phosphorylation is the mechanism by which glucagon, and perhaps other hormones whose actions are mediated by adenosine 3',5'-cyclic phosphate (cyclic AMP), induce RNA synthesis in target tissues. The incorporation of (32)P-phosphate into lysine-rich histone is determined by isolation of a tryptic peptide which contains the phosphorylated serine residue. This peptide is identical to the major tryptic phosphopeptide obtained from lysine-rich histone after phosphorylation in vitro by a purified cyclic AMP-dependent liver histone kinase preparation; the partial sequence Lys-Ala-SerPO(4)(Thr,Ser,Glu,Pro(2),Gly,Val,Ile,Leu)Lys has been determined for the peptide. Hydrocortisone and adrenocorticotrophic hormone do not cause a detectable increase in histone phosphorylation in liver. However, insulin, which like glucagon induces an actinomycin sensitive synthesis of liver enzymes, also causes increased histone phosphorylation.
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PMID:Phosphorylation of liver histone following the administration of glucagon and insulin. 431 47

The heterogeneity of crystalline bovine (ox)/porcine glucagon has been examined by gel filtration and ion-exchange chromatography. A strongly basic peptide that reacted well with antibodies to bovine/porcine glucagon was isolated and its primary structure was determined. The amino-acid sequence of the NH(2)-terminal 29 residues of the 4500-dalton peptide is identical with that of intact bovine or porcine glucagon. The remaining eight residues at its COOH-terminus are Lys-Arg-Asn-Asn-Lys-Asn-Ile-Ala. Small amounts of other glucagon-immunoreactive peptides having molecular weights ranging from 3700 to 9000 were also detected in crystals of bovine/porcine glucagon. We propose that the 37-residue peptide is a fragment of bovine or porcine proglucagon.
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PMID:Isolation of a glucagon-containing peptide: primary structure of a possible fragment of proglucagon. 452 66

The effect of 20 L-amino acids upon pancreatic glucagon secretion has been studied in conscious dogs. Each amino acid was administered intravenously over a 15 min period in a dose of 1 mmole/kg of body weight to a group of four or five dogs. Pancreatic glucagon and insulin were measured by radioimmunoassay. 17 of the 20 amino acids caused a substantial increase in plasma glucagon. Asparagine had the most glucagon-stimulating activity (GSA), followed by glycine, phenylalanine, serine, aspartate, cysteine, tryptophan, alanine, glutamate, threonine, glutamine, arginine, ornithine, proline, methionine, lysine, and histidine. Only valine, leucine, and isoleucine failed to stimulate glucagon secretion, and isoleucine may have reduced it. No relationship between glucagon-stimulating activity and insulin-stimulating activity was observed. The amino acids which enter the gluconeogenic pathway as pyruvate and, which are believed to provide most of the amino acid-derived glucose, had a significantly greater GSA than the amino acids which enter as succinyl CoA or as alpha-ketoglutarate. However, pyruvate itself did not stimulate glucagon secretion. The R-chain structure of the amino acid did not appear to be related to its GSA, except that the aliphatic branched chain amino acids, valine, leucine, and isoleucine, were devoid of GSA.
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PMID:Glucagon-stimulating activity of 20 amino acids in dogs. 463 19

Albumin synthesis was measured in the isolated perfused rat liver by using the livers of both well-fed and starved rats. Starvation markedly decreased albumin synthesis. The livers from starved rats were unable to increase synthesis rates after the addition to the perfusates of single amino acids or the addition of both glucagon and tryptophan. Arginine, asparagine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, threonine, tryptophan and valine, added together to ten times their normal peripheral blood concentrations, restored synthesis rates to normal. The plasma aminogram (i.e. the relative concentrations, of amino acids) was altered by depriving rats of protein for 48h. The use of blood from the deprived rats as perfusate, instead of normal blood, decreased albumin synthesis rates significantly by livers obtained from well-fed rats. The addition of single amino acids, including the non-metabolizable amino acid, alpha-aminoisobutyric acid, to the above mixture increased albumin synthesis rates to normal values. It is concluded that amino acids play an important role in the control of albumin synthesis and that more than one mechanism is probably involved.
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PMID:The effects of amino acids on albumin synthesis by the isolated perfused rat liver. 465 17

Splanchnic and leg exchange of glucose, lactate, pyruvate, and individual plasma amino acids was studied in diabetics 24 hr after withdrawal of insulin and in healthy controls. Measurements were made in the basal postabsorptive state and during the administration of glucose at a rate of 2 mg/kg per min for 45 min. In the basal state, net splanchnic glucose production did not differ significantly between diabetics and controls. However, splanchnic uptake of alanine and other glycogenic amino acids was 1(1/2)-2 times greater in the diabetics, while lactate and pyruvate uptake was increased by 65-115%. Splanchnic uptake of these glucose precursors could account for 32% of hepatic glucose output in the diabetics, as compared to 20% in the controls. This increase in precursor uptake was a consequence of a two- to threefold increment in fractional extraction of these substrates inasmuch as arterial levels of alanine, glycine, and threonine were reduced in the diabetics, while the levels of the remaining substrates were similar in the two groups. Peripheral output of alanine and other glycogenic amino acids as reflected in arterio-femoral venous differences was similar in both groups. An elevation in arterial valine, leucine, and isoleucine was observed in the diabetics, but could not be accounted for on the basis of alterations in splanchnic or peripheral exchange of these amino acids. Administration of glucose (2 mg/kg per min) for 45 min resulted in an 80% reduction in splanchnic glucose output in controls, but failed to inhibit hepatic glucose release in the diabetics despite a twofold greater increment in arterial glucose levels. In both groups no consistent changes in arterial glucagon were observed during the infusion. It is concluded that in nonketotic diabetics (a) total splanchnic output of glucose is comparable to controls, but the relative contribution of gluconeogenesis may be increased by more than 50%; (b) accelerated splanchnic uptake of glucose precursors is a consequence of increased hepatic extraction of available substrates rather than a result of augmented substrate supply; and (c) the failure of glucose infusion to inhibit hepatic glucose output suggests that the exquisite sensitivity of the liver to the infusion of glucose in normal man is a consequence of glucose-induced insulin secretion.
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PMID:Splanchnic and peripheral glucose and amino acid metabolism in diabetes mellitus. 503 28

Effects of the novel gastrointestinal polypeptide PHI with N-terminal histidine, C-terminal isoleucine amide, and 27 amino acids have been studied in isolated perfused rat pancreas. PHI increased the release of insulin, glucagon, and somatostatin. The amounts of these hormones released were strictly dependent on the prevailing glucose concentrations. In the absence of glucose, PHI (1 nmol/liter) stimulated glucagon release. In the presence of 4.4 and 6.7 mmol/liter glucose, the same dose of this peptide stimulated insulin and somatostatin release. In the presence of 16.7 mmol/liter glucose, only insulin secretion was increased by PHI. When arginine was used as a secretagogue, PHI (10 nmol/liter) potentiated secretion of insulin, glucagon, and somatostatin. Thus, PHI may take part in the regulation of the function of the pancreatic A, B, and D cells.
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PMID:Effects of PHI on hormonal secretion from perfused rat pancreas. 613 56


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