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)

The effects on the conceptus of persistently decreased maternal plasma amino acid concentrations were studied in pregnant rats by the infusion of glucagon (0.21 mg/day) to the mother from day 14 to 20 of gestation with a subcutaneous, osmotically driven minipump. Controls received diluent. The experimental animals either had normal caloric intake and weight gain, or diminished caloric intake with no weight gain. Both experimental groups exhibited a decrease in plasma total amino acid concentration of approximately 50%. Maternal plasma glucose and insulin concentrations were unaffected except for slight decreases in the low weight gain group. At cesarean section on day 20, fetal weight was unaffected in the normal weight gain group, while the low weight gain animals exhibited intrauterine growth retardation. Fetal plasma glucose and insulin concentrations were unaffected. Despite the marked decrease in maternal plasma total amino acid concentration, fetal plasma total amino acid concentration was unaffected. Individual plasma amino acid concentrations in the normal weight gain mothers and fetuses revealed a spectrum of changes. Some maternal amino acids were decreased by more than 60% (alpha-aminobutyric acid, asparagine, threonine, glutamine, alanine) while others were unaffected (tyrosine, tryptophan, phenylalanine, histidine). In general, amino acids that were decreased in the mother exhibited no change or a lesser decrease in fetal plasma concentration, while those that were unaffected in the mothers showed increased fetal concentrations. Fetuses from the low weight gain mothers had plasma amino acid profiles that were similar to those of the normal weight gain mothers.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Preserved fetal plasma amino acid concentrations in the presence of maternal hypoaminoacidemia. 379

The role of polyamines in the control of phenylalanine hydroxylase phosphorylation state and enzymic activity was investigated. Pre-treatment of liver cells with spermine (1 mM) abolishes the glucagon (1 nM)-stimulated increase in hydroxylase phosphorylation. Concurrently there is a decrease in phenylalanine hydroxylation flux, reflecting decreased enzyme activity; 50% inhibition occurs at approx. 10 microM-spermine. These results are discussed in the context of reports concerning the properties of protein phosphatase 2A.
 ...
PMID:The polyamine-dependent modulation of phenylalanine hydroxylase phosphorylation state and enzymic activity in isolated liver cells. 380 Aug 81

A thiol peptidase that catalyzes at near neutral pH the hydrolysis of insulin, the isolated A and B chains of insulin, and glucagon was purified from rat liver cytosol by fractionation on Sephadex G-200, Affi-Gel Blue, and Spherogel TSK-G 3000 SW. The purified enzyme showed a single component by chromatography on a Spherogel TSK column and by gel filtration on a Sephadex G-200 column. The native enzyme has a molecular weight of approximately 180,000 and consists of two subunits having pI's of 5.9 and 6.3. Studies on its substrate specificity showed that the purified enzyme degrades glucagon, insulin, insulin B chain, and insulin A chain, but it does not degrade proinsulin, ACTH, or denatured hemoglobin. Kinetic analyses were performed on three substrates. The Km values were: 34 nM for insulin, 276 nM for insulin B chain, and 3.5 microM for glucagon. The kcat and Vm/Km values were glucagon greater than B chain greater than insulin. Thus, the enzyme has the highest affinity/lowest efficiency for insulin, an intermediate affinity/intermediate efficiency for B chain of insulin and the lowest affinity/highest efficiency for glucagon. The effect of several potential activators and inhibitors on the enzyme's activity was investigated. The enzyme activity was markedly inhibited by N-ethylmaleimide, p-chloromercuribenzoic acid, iodoacetamide, and Np-tosyl-L-phenylalanine chloromethyl ketone (TPCK), and was partially inhibited by dithiothreitol, by the chelating agents EDTA and EGTA, and by phenylmethylsulfonyl fluoride (PMSF). Bacitracin inhibited the activity of the enzyme, but the protease inhibitors aprotinin, leupeptin, pepstatin, and phosphoramidon had little or no effect. Reduced glutathione, iodoacetate, and N alpha,p-tosyl-L-lysine chloromethyl ketone (TLCK) also had little or no effect on the enzyme activity.
 ...
PMID:Purification and characterization of a rat liver cytosol neutral thiol peptidase that degrades glucagon, insulin, and isolated insulin A and B chains. 388 Oct 83

Chronic (10-day) diabetes was associated with increased metabolic flux through phenylalanine hydroxylase in isolated liver cells. This flux was stimulated by 0.1 microM-glucagon, but not by 10 microM-noradrenaline; 0.1 microM-insulin affected neither basal nor glucagon-stimulated flux. The increased rate of phenylalanine hydroxylation in diabetes was accompanied by parallel increases in enzyme activity (as measured with artificial cofactor) and immunoreactive-enzyme-protein content. In contrast with total protein synthesis, which decreased, phenylalanine hydroxylase synthesis persisted at the control rate in cells from diabetic animals. These findings are discussed in relation to the hormonal regulation of the hydroxylase and the known metabolic consequences of chronic diabetes.
 ...
PMID:The effect of experimental diabetes on phenylalanine metabolism in isolated liver cells. 388 93

The work presented here aims at investigating the in vitro relationship between amino acids and pancreatic hormonal release in the suckling rat. Among the 20 most usual amino acids, 12 of them were tested on perifused pieces of pancreas in 5.5-day-old rats at a low glucose concentration. Their effects were compared to those induced by a 20 amino acid mixture. A 20 amino acid mixture (10.3 mM) stimulated glucagon and insulin release (154 and 208%, respectively). In the mixture, the 4 pooled amino acids Ala-Gly-Ser-Thr (at 1.4 instead of 4.2 mM) did not induce further modification of the glucagon or insulin release. However, the 3 branched chain amino acids Ile-Leu-Val (at 2.9 instead of 1.4 mM) or the following amino acids Arg-Asn-Phe-Pro-Tyr (at 3.2 instead of 1.6 mM) modulated glucagon or insulin release in the presence of the amino acid mixture. In the absence of Ile-Leu-Val, the amino acid mixture had no effect on the insulin release: 122 compared to 208%. This seems specific to the chemical nature of Ile-Leu-Val since in the absence of Arg-Asn-Phe-Pro-Tyr, the amino acid mixture was still effective on the insulin release (178 compared to 208%). In the absence of Ile-Leu-Val, the amino acid mixture was effective on glucagon release, and revealed the cellular specificity of the branched chain amino acid action.
 ...
PMID:Chemical specificity of the effects of branched chain amino acids on glucagon and insulin release in the suckling rat. 389 29

Hormonal control of the phosphorylation of phenylalanine hydroxylase was studied by using rat liver cells incubated with [32P]Pi. After immunoprecipitation from cell extracts, the hydroxylase was subjected to proteinase digestion and subsequent sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. V8-proteinase digestion yielded one major 32P-labelled fragment, of approx. 9 kDa. Chymotrypsin digestion gave five 32P-labelled fragments ranging from approx. 39 kDa to approx. 10 kDa. Noradrenaline (10 microM) and glucagon (0.1 microM) enhanced the 32P content of all peptide fragments uniformly. Phorbol ester, in contrast with ionophore A23187, did not stimulate enzyme phosphorylation or enhance phenylalanine metabolism in liver cells. These results are discussed in relation to the nature of the protein kinase(s) that mediate phosphorylation of phenylalanine hydroxylase in liver cells.
 ...
PMID:Phosphopeptide analysis of phenylalanine hydroxylase isolated from liver cells exposed to hormonal stimuli. 395 49

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.
 ...
PMID:Primary structure of glucagon and a partial sequence of oxyntomodulin (glucagon-37) from the guinea pig. 404 53

Cathepsins M and B from rabbit liver lysosomes were separated by chromatography on Ultrogel AcA34 at low ionic strength and purified to homogeneity, and their catalytic and molecular properties were compared. Cathepsin M was relatively inactive with synthetic peptide substrates. Thus, it hydrolyzed benzoyl arginine naphthylamide at only one-fifth the rate observed with cathepsin B, and no activity was detected with Gly-Phe naphthylamide which is a relatively good substrate for cathepsin B. On the other hand, cathepsin M exhibited a preference for protein substrates. It was more active than cathepsin B in catalyzing the inactivation of the following enzymes: rabbit muscle or liver fructose-1,6-bisphosphate aldolases, rabbit liver fructose-1,6-bisphosphatase and pyruvate kinase, yeast glucose-6-phosphate dehydrogenase, and rabbit muscle glyceraldehyde-3-phosphate dehydrogenase. With glucagon as substrate, both enzymes showed similar peptidyl dipeptidase activities with some minor differences in peptide bond specificity. Cathepsins M and B are similar in size, with apparent molecular weights of 30,200 for cathepsin M and 28,800 for cathepsin B, and in amino acid composition and carbohydrate content. Each contains approximately 2-3 equivalents/mol glucosamine, 3 equivalents/mol mannose, and no fucose or galactosamine. They also show similar microheterogeneity in sodium dodecylsulfate-gel electrophoresis and isoelectric focusing; this microheterogeneity is probably related to differences in glycosylation. Extensive homology in primary structure for the two proteins was indicated by the similar patterns of peptides formed on digestion with trypsin.
 ...
PMID:Purification and properties of rabbit liver cathepsin M and cathepsin B. 406 7

Combination of Fast Atom Bombardment Tandem Mass Spectrometry with Amino Acid Analysis assigns the amino acid sequence of the Manduca sexta adipokinetic hormone as pGlu-Leu-Thr-Phe-Thr-Ser-Ser-Trp-GlyNH2. Similarities and differences with other invertebrate hormones and with mammalian glucagon are discussed.
 ...
PMID:Amino acid sequence of Manduca sexta adipokinetic hormone elucidated by combined fast atom bombardment (FAB)/tandem mass spectrometry. 407 73

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).
 ...
PMID:The isolation and characterization of serum albumin from the ostrich (Struthio camelus). 409 40


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>