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

The organ distribution of rat histidine-pyruvate aminotransferase isoenzymes 1 and 2 was examined by using an isoelectric-focusing technique. Isoenzyme 1 (pI8.0) is present only in the liver and its activity is increased by the injection of glucagon, whereas isoenzyme 2 (pI5.2) is distributed in all tissues (liver, kidney, brain and heart) tested, and is not affected by glucagon injection. Isoenzyme 2 of the liver, kidney, brain and heart was purified by the same procedure and characterized. Isoenzyme 2 preparations from these four tissues were nearly identical in physical and enzymic properties. These properties differed from those previously found for the highly purified isoenzyme 1 preparation of rat liver. Isoenzyme 2 was active with pyruvate but not with 2-oxoglutarate as amino acceptor. Amino donors were effective in the following order of activity: tyrosine greater than histidine greater than phenylalanine greater than kynurenine greater than tryptophan. Very little activity was found with 5-hydroxytryptophan. The apparent Km for histidine was about 0.45 mM. The Km for pyruvate was about 4.5 mM with histidine as amino donor. The amino-transferase activities of isoenzyme 2 towards phenylalanine and tyrosine were inhibited by histidine. The ratio of aminotransferase activities towards these three amino acids was constant through gel filtration, electrophoresis, isoelectric focusing and sucrose-density-gradient centrifugation of the purified isoenzyme 2 preparations. These results suggest that these three activities are properties of the same enzyme protein. Sephadex G-150 gel filtration and sucrose-density-gradient centrifugation yielded mol.wts. of approx. 95000 and 92000 respectively. The pH optimum was between 9.0 and 9.3.
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PMID:Organ distribution of rat histidine-pyruvate aminotransferase isoenzymes. 1 Aug 88

Systematic analysis of the hydrolysis of benzyloxycarbonyl (Cbz)-dipeptides by cathepsin A [EC 3.4.12.1] purified from rat liver lysosomes showed that multiple forms of cathepsin A preferentially cleave peptide bonds with leucine, methionine, and phenylalanine. Cbz-Met-Met, -Met-Phe, -Phe-Met, and -Phe-Ala were hydrolyzed 6 to 8 times faster than the standard substrates, Cbz-Glu-Phe and Cbz-Glu-Tyr. The pH optima of the hydrolyses were 4.6 to 5.8. Hydrolysis of peptide bonds with glycine, isoleucine, and proline was very slow, but the rate depended on the nature of the adjacent amino acids. Proteins such as albumin, cytochrome c, gamma-globulin, hemoglobin, histone, myoglobin, and myosin were scarecely degraded. Peptide hormones, such as glucagon and adrenocorticotropic hormone (ACTH) were hydrolyzed markedly with optimum pH's of 4.5 and 4.6, respectively. Angiotensin I, II, bradykinin, Lys- and Met-Lysbradykinin (kallidin and Met-kallidin), and substance P were also hydrolyzed at appreciable rates. pH optima for these peptide hormones were 5.2 to 5.6. On the other hand, insulin and its A chain, luteinizing hormone-releasing hormone (LH-RH), oxytocin and vasopressin were cleaved slowly. In the hydrolyses of glucagon and other peptides, multiple forms of rat liver lysosomal cathepsin A again showed a carboxypeptidase nature, cleaving peptide bonds sequentially from the carboxyl terminal. Almost all of the amino acids were cleaved on prolonged incubation. Vaso-activites of angiotensin II and bradykinin were rapidly lost on hydrolysis by cathepsin A. Lysosomal cathepsin C [dipeptidylaminopeptidase I, EC 3.4.14.1] also activated angiotensin II, but did not inactive bradykinin. Cathepsin A, therefore, can be regarded as one of the lysosomal angiotensinases and kinases. No distinct differences were observed between the multiple forms of cathepsin A in these hydrolyses and inactivations of peptides.
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PMID:Studies on cathepsins of rat liver lysosomes. III. Hydrolysis of peptides, and inactivation of angiotensin and bradykinin by cathepsin A. 1 61

Hepatic phenylalanine(histidine):pyruvate aminotransferase activity is much higher in the mouse and rat than in other animal species (human, guinea-pig, rabbit, pig, dog and chicken). The activity is elevated in the mouse and rat by the injection of glucagon but not in other species (guinea-pig, rabbit and chicken). The enzyme was purified from the mitochondrial fraction of mouse liver to homogeneity as judged by polyacrylamide disc gel electrophoresis in the presence of dodecylsulphate. With histidine as amino donor, the enzyme was active with pyruvate, oxaloacetate and hydroxypyruvate as amino acceptors but not with 2-oxoglutarate. Effective amino donors were histidine, phenylalanine and tyrosine with pyruvate, and methionine, serine and glutamine with phenylpyruvate. The apparent Km for histidine was about 6.9 mM with pyruvate and that for pyruvate was 21 mM with histidine. The enzyme is probably composed of two identical subunits with a molecular weight of approximately 40000. The pH optimum was near 9.0. Isoelectric focusing of the purified enzyme resulted in the detection of four forms with pI 6.0, 6.2, 6.5 and 6.7, respectively, all of which were responsive to glucagon. These four forms were nearly identical with the purified enzyme before the focusing with respect to physical and enzymic properties. A possible mechanism of this multiplicity is discussed.
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PMID:Species distribution and properties of hepatic phenylalanine (histidine):pyruvate aminotransferase. 1 70

Aromatic-amino-acid-glyoxylate aminotransferase was highly purified from the mitochondrial fraction of livers from monkey and glucagon-injected rats. The two enzyme preparations showed physical and enzymic properties different from a kynurenine aminotransferase previously described. The two enzymes had nearly identical molecular weights (approximate 80 000), isoelectric points (pH 8.0) and pH optima (pH 8.0 - 8.5). However, a difference in substrate specificity was observed between the two enzymes. Both enzymes utilized glyoxylate, pyruvate, hydroxypyruvate and 2-oxo-4-methyl-thiobutyrate as effective amino acceptors. 2-Oxoglutarate was active for rat enzyme but not for monkey enzyme. With glyoxylate, amino donors were effective in the following order of activity; phenylalanine greater than histidine greater than tyrosine greater than tryptophan greater than 5-hydroxytrypotphan greater than kynurenine for the rat enzyme, and phenylalanine greater than kynurenine greater than histidine greater than tryptophan greater than 5-hydroxy-tryptophan for the monkey enzyme.
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PMID:Purification and characterization of aromatic-amino-acid-glyoxylate aminotransferase from monkey and rat liver. 2 37

Sepsis is a major catabolic insult resulting in modifications in carbohydrate and fat energy metabolism, and leading to increased muscle breakdown and nitrogen loss. Insulin resistance, which develops in sepsis, decreases glucose utilization, but plasma insulin levels are sufficiently elevated to prevent lipolysis, resulting in a further energy deficit. The availability of fuels in sepsis is therefore limited, and the body resorts to muscle breakdown, gluconeogenesis, and amino acid oxidation for energy supply. Previous work has not defined, however, the exact alterations in amino acid metabolism. Therefore, the following studies were undertaken. Blood samples were drawn from fifteen patients in whom the diagnosis of sepsis was clinically established; the samples were analyzed for amino acid, beta-hydroxyphenylethanolamines, glucose, insulin and glucagon concentrations. The plasma amino acid pattern observed was characterized by an increase in total amino acid content, due mainly to high levels of the aromatic amino acids (phenylalanine and tyrosine) and the sulfur-containing amino acids (taurine, cystine and methionine). Alanine, aspartic acid, glutamic acid and proline were also elevated, but to a lesser degree. The branched chain amino acids (valine, leucine and isoleucine) were within normal limits, as were glycine, serine, threonine, lysine, histidine and tryptophan. Those patients who did not survive sepsis had higher levels of aromatic and sulfur-containing amino acids as compared to those patients surviving sepsis. On the other hand, those patients surviving sepsis had higher levels of alanine and the branched chain amino acids. In a second group of five patients with overwhelming sepsis accompanied by a state of metabolic encephalopathy, a parenteral nutrition solution consisting of 23% dextrose, and an amino acid formulation enriched with branched chain amino acids was administered. In these five patients, normalization of the plasma amino acid pattern and reversal of encephalopathy was observed. The following sequence of events may be postulated: The septic patient develops insulin resistance in the peripheral tissues, primarily muscle, while the adipose tissue is much less affected. The insulin resistance and the inability to utilize fat leads to increased muscle proteolysis. Muscle breakdown results in release into the blood of enormous amounts of various amino acids; the muscle itself is able to oxidize the branched chain amino acids, supplying the muscles' own energy requirements and alanine for gluconeogenesis. The extensive muscle proteolysis coupled with relative hepatic insufficiency occurring early in sepsis results in the appearance in the plasma of high levels of most of the amino acids present in muscle, particularly the aromatic and the sulfur-containing amino acids. The outcome of patients with sepsis might be positively affected by combined therapy with glucose, insulin and branched chain amino acids.
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PMID:Amino acid derangements in patients with sepsis: treatment with branched chain amino acid rich infusions. 9 98

Two groups (each of 6 moderately ill, protein-depleted patients) were infused daily for 7 days. Mean 7 day nitrogen (N) balances with infusions of 0.83 and 1.83 g of a defined amino acid mixture (containing further nutrients but no other source of energy)/kg ideal body wt/day were -3.66 and +1.54 g/day, respectively (P less than 0.025) when adjusted for changes in body urea and estimated miscellaneous N losses. Concentrations of plasma free fatty acids, immunoreactive insulin and glucagon, and of blood glucose, pyruvate, lactate and glycerol were indistinguishable on corresponding treatment days in the 2 groups but blood ketone bodies were lower in the 1.83 g/kg group. Blood amino acid concentrations of alanine, valine, leucine, and isoleucine were similar, whereas those of phenylalanine, histidine, serine, and arginine were higher, and glutamine lower, in the 1.83 g/kg group. The data confirm that not only can body protein mass be maintained, but a net positive N retention achieved, in such patients, through provision of exogenous amino acids and concurrent mobilization of endogenous energy stores. Of note is that this fat mobilization can occur without plasma free fatty acids and/or significant blood ketone body elevations. An infusion of 2, rather than 1 g/kg/day seems suitable in the situation examined.
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PMID:Intravenous protein-sparing therapy in patients with gastrointestinal disease. 11 60

Alloxan diabetic rats maintained on protamine zinc insulin for two weeks were used for these studies. Hepatocytes were isolated from these rats at various time intervals after withdrawal of insulin (0, 48, 72 and 96 hr). Gluconeogenesis with various concentrations of lactate and fructose was studied. Both lactate and fructose stimulated gluconeogenesis and showed progressive increases in glucose production up to 72 hr after the insulin withdrawal. Glucose production decreased at 96 hr. Protein synthesis in isolated hepatocytes from diabetic liver cells, as measured by the incorporation of radioactive isoleucine, valine and phenylalanine into protein, showed a decrease (5- to 6-fold) with time after insulin withdrawal. Glucagon (10(-6)M) alone increased cyclic AMP levels 10-fold in liver cells, in isolated cells from rats maintained on insulin (0 hr) or from rats withdrawn from insulin for 48 hr. The ability of glucagon to elevate cyclic AMP levels in isolated diabetic liver cells decreases 72 hr following insulin withdrawal.
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PMID:Studies on gluconeogenesis, protein synthesis and cyclic AMP levels in isolated hepatocytes from alloxan diabetic rats. 17 99

A single injection of either isoproternol or N6, O2'-dibutyryl adenosine 3':5'-monophosphate (dibutyryl cyclic AMP) results in an inhibition in the rate of [3H]thymidine incorporation into DNA of differentiating cardiac muscle of the neonatal rat. This inhibition is not due to substantially altered cellular uptake or catabolism of [3H]thymidine. Inhibition of [3H]thymidine incorporation by isoproterenol or dibutyryl cyclic AMP is potentiated by theophylline. Maximal inhibition (95%) is observed 24 h after administration of isoproterenol, and the rate of incorporation returns to a value 80% of control by 72 h. Norepinephrine also inhibits [3H]thymidine incorporation whereas cyclic GMP, N2, 02-Dibutyryl guanosine 3':5'-monophosphate (dibutyryl cyclic GMP), and phenylephrine have little effect. Equilibrium sedimentation analysis of cardiac muscle DNA in neutral and alkaline cesium chloride gradients using bromodeoxyuridine as a density label indicate that isoproterenol and dibutyryl cyclic AMP inhibit [3H]thymidine incorporation into DNA that is replicating semiconservatively. Administration of isoproterenol or dibutyryl cyclic AMP to neonatal rats inhibits by approximately 60% the incorporation of [3H]thymidine into DNA of tissue slices of cardiac muscle prepared 16 h later. [3H]Thymidine incorporation into DNA of tissue slices is into chains that were growing in vivo. This incorporation is linear for at least 4 h of incubation and is inhibited by isoproterenol and dibutyryl cyclic AMP. Inhibition is not due to altered cellular uptake of [3H]thymidine nor is it due to a cytotoxic action. Several other compounds which elevate intracellular levels of cyclic AMP (epinephrine, norepinephrine, glucagon, and prostaglandin E1) also inhibit [3H]thymidine incorporation into DNA or cardiac muscle tissue slices. Cyclic GMP, dibutyryl cyclic GMP, sodium butyrate, and phenylephrine have little effect. Isoproterenol administered together with theophylline to neonatal rats signficantly stimulates the in corporation of [3H]phenylalanine into total cardiac muscle protein and into myosin. This enhanced incorporation may be due in part to an increase in the cellular uptake of [3H]phenylalanine. DNA synthesis decreases progressively in differentiating cardiac muscle of the rat during postnatal development and essentially ceases by the middle of the third week (Claycomb, W. C. (1975) J. Biol. Chem. 250, 3229-3235). In reviewing the literature it was found that this decline in synthetic activity correlates temporally with a progressive increase in tissue concentrations of norepinephrine and cyclic AMP and with the anatomical and physiological development of the adrenergic nerves in this tissue. Because of these facts and data presented in this report it is proposed that cell proliferation and cell differentiation in cardiac muscle may be controlled by adrenergic innervation with norepinephrine and cyclic AMP serving as chemical mediators.
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PMID:Biochemical aspects of cardiac muscle differentiation. Possible control of deoxyribonucleic acid synthesis and cell differentiation by adrenergic innervation and cyclic adenosine 3':5'-monophosphate. 18 91

A fragment of glucagon encompassing its first six NH2-terminal residues (His-Ser-Gln-Gly-Thr-Phe) binds to the glucagon receptor and stimulates adenylate cyclase activity in rat liver plasma membranes. Glucagon1-6 is a partial agonist since it stimulates, at saturating concentrations, to the extent of 75% of the maximal activity given by the native hormone. The binding affinity and potency of glucagon1-6 are 0.001% the native hormone. Discussed are the implications of these findings on the structure-function relationships required for the action of glucagon and for preparing clinically useful analogs of the hormone.
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PMID:Glucagon1-6 binds to the glucagon receptor and activates hepatic adenylate cyclase. 21 70

Preoperative and serial postoperative clinical, cardiovascular, physiologic, and metabolic studies were carried out on 86 patients undergoing coronary artery bypass surgery (CABG); and 48 patients undergoing abdominal general surgical procedures (GSEL). Multivariable statistical analysis of these data showed the patients to be in different physiologic states and to manifest several types of recovery trajectories that could not be discerned on clinical grounds alone. The CABG patients followed one of three types of cardiogenic recovery trajectories. In contrast, GSEL patients show a normal recovery trajectory different from all CABG types. When sepsis develops, and exaggerated stress response (A state) occurs, with increased oxygen consumption and a pattern of amino acids, fat, and glucose breakdown products, which is heightened but similar to the response of nonseptic GSEL patients. With progression of sepsis severity, an unbalanced hyperdynamic recovery trajectory (B state) develops in which a decrease in oxygen consumption is associated with increases in the aromatic amino acids tyrosine, tryptophane, and phenylalanine; and decreases in the branched-chain amino acids, leucine and isoleucine. Triglycerides rise as keto acids fall, but both lactate and pyruvate rise. Glucagon is persistently high, regardless of insulin levels. The quantifiably different physiologic recovery trajectories reflect altered hormone and metabolic states and imply different responses to therapy.
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PMID:The physiologic recovery trajectory as the organizing principle for the quantification of hormonometabolic adaptation to surgical stress and severe sepsis. 31 78


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