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

A patient in whom Cushing syndrome had been diagnosed at the age of 23 was found 14 years later to have subclinical diabetes mellitus, subcutaneous calcified fat tissue necroses, and hypergastrinemia suggesting Zollinger-Ellison syndrome. Histopathologic investigation revealed pancreatic adenomatosis of the glucagon producing A2-cells with accompanying B-cell hyperplasia, and hyperplasia of the adrenal cortex. The origin of the increased serum gastrin concentration in this patient is not yet known. The significance of A2-cell proliferation in Zollinger-Ellison syndrome and and in multiple endocrine adenomatosis is discussed.
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PMID:[Glucagon producing adenomatosis of Islands of Langerhans with polyendocrine symptoms]. 1 53

Induction of delta-aminolevulinic acid synthetase by allylisopropylacetamide in organ-cultured chick embryo liver was not appreciably influenced by any of cycli AMP, dibutyryl cyclic AMP, theophylline, glucose, insulin, glucagon, epinephrine, isoproterenol, and hydrocortisone, whereas the activity of tyrosine aminotransferase significantly increased in response to cyclic AMP and some of those hormones. Accumulation of delta-aminolevulinic acid synthetase in the cultured liver cytosol fraction was not appreciably increased by the addition of dibutyryl cyclic AMP or insulin to the incubation medium. Apparently the behaviors of the induction of delta-aminolevulinic acid synthetase in chick embryo liver in ovo and in vitro differ from those in the livers of adult chicken and rat. High concentrations of chloramphenicol suppressed significantly the allylisopropylacetamide-induced increase of delta-aminolevulinic acid synthetase as well as incorporation of 14C-leucine into proteins. The activity of tyrosine aminotransferase, however, was rather increased when relatively low concentrations of chloramphenicol were added to the medium.
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PMID:Comparative studies of the effects of cyclic AMP, various hormones and chloramphenicol on the induction of delta-aminolevulinic acid synthetase and tyrosine aminotransferase in the organ-cultured chick embryo liver. 1 73

A transient rise in cyclic guanosine 3' : 5' monophosphate (c-GMP) in the liver was observed in rats in vivo 10--20 min after partial hepatectomy. A similar increase in c-GMP in the liver was also found in rats in vivo 15 min after infusion of TGH solution (a mixture of triiodothyronine, glucagon, and heparin). In both cases, inductions of ornithine decarboxylase [EC 4.1.1.17] and tyrosine aminotransferase [EC 2.6.1.5] were found 4 hr after the beginning of the experiments. Later, 22 hr after the surgical intervention or hormone infusion, thymidine kinase [EC 2.7.1.21] was activated and liver slices were able to incorporate [3H]thymidine into DNA. These biochemical phenomena were observed commonly in regenerating liver as well as in the liver of rats infused with TGH solution. c-GMP, but not c-AMP, could induce ornithine decarboxylase and tyrosine aminotransferase in isolated, perfused liver.
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PMID:Involvement of cyclic GMP in the initial stage of hepatocytes proliferation. 1 43

After glucagon injection, rats showed virtually identical percentage increases in hepatic histidine-pyruvate aminotransferase and serine-pyruvate aminotransferase activities, both in the mitochondria and in the cytosol. Histidine-pyruvate aminotransferase isoenzyme 1, with pI8.0, was purified to homogeneity from the mitochondrial fraction of liver from glucagon-injected rats. The purified enzyme catalysed transamination between a number of amino acids and pyruvate or phenylpyruvate. For transamination with pyruvate, the activity with serine reached a constant ratio to that with histidine during purification, which was unchanged by a variety of treatments of the purified enzyme. Serine was found to act as a competitive inhibitor of histidine transamination, and histidine of serine transamination. These results suggest that histidine-pyruvate amino-transferase isoenzymes 1 is identical with serine-pyruvate aminotransferase. The enzyme is probably composed of two identical subunits with mol. wt. approx. 38000. The absorbance maximum at 410 nm and the inhibition by carbonyl reagents strongly indicate the presence of pyridoxal phosphate.
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PMID:Identity of isoenzyme 1 of histidine-pyruvate aminotransferase with serine-pyruvate aminotransferase. 1 42

The specificity of bovine spleen cathepsin B2 has been investigated by means of some natural oligo- and polypeptides, i.e. glucagon, melittin, insulin A and B chain, bradykinin, angiotensin I and II, oxytocin ACTH, clupein and salmin. The enzyme is primarily a carboxypeptidase which hydrolyzes peptide linkages of most amino acids common to proteins. In addition, cathepsin B2 displays amidase and esterase activity without requiring a free carboxyl group. The main pH optimum is between 4 and 5, in some cases higher.
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PMID:On the specificity of bovine spleen cathepsin B2. 1 11

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

The effectiveness of dietary and hormonal treatments in inducing several pyridoxal phosphate-(PLP)-dependent enzymes has been examined in vitamin B-6 deficient rats. Holo- and apoenzymes of serine dehydratase and ornithine aminotransferase were inducible in both control and deficient rats by feeding them 80% casein diets or by injecting them with glucagon. Holo- and apotyrosine aminotransferase were induced in both control and deficient rats by injecting them with glucagon or with dexamethasone phosphate. Phosphoenolpyruvate carboxykinase, a non-PLP-dependent enzyme, was inducible in both control and deficient rats by glucagon treatment if the rats were fed, but not if they had been starved. The degree of induction of certain enzymes depended upon whether rats were fed ad libitum, starved overnight, or fed a protein-free diet prior to the induction period. Phosphoenolpyruvate carboxykinase activities were about the same in both control and deficient rats. In vitamin B-6 deficient rats, both uninduced and induced activities of serine dehydratase, ornithine aminotransferase, and tyrosine aminotransferase assayed in the prsence of PLP, but not in its absence, either equaled or exceeded control values under most experimental conditions. Synthesis of excess of apoenzyme of PLP-dependent enzymes generally accounted for the high total enzyme activity in deficient rats. Differences between values for control and deficient rats could not be accounted for by differences in liver cyclic AMP concentrations nor were they apparently related to reduced food intake of the deficient rats. High apoenzyme concentration during depletion of coenzyme would tend to prevent depletion of active enzyme.
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PMID:Induction of pyridoxal phosphate-dependent enzymes in vitamin B-6 deficient rats. 1 69

Examination of glucose kinetics, pancreatic alpha and beta cell function, plasma lipids, urinary acidification and calcium excretion has been undertaken in a patient with hereditary fructose intolerance. This case was unusual as it was associated with insulin-requiring diabetes, type IV hyperlipemia, hypercalciuria and renal calculi. He also demonstrated the previously described fructose-induced defect of urine acidification. Glucagon and C-peptide assays showed that the pancreatic alpha cells were stimulated by fructose and that the beta cells did not respond to fructose. It is not known whether the latter was due to his diabetes or to the lack of a beta cell response to this sugar. Primed 14C-glucose infusions were used for the first time to study nonsteady state glucose kinetics in man. They showed that, 24 hours after the last insulin injection and under basal conditions, the glucose concentrations increased because glucose production exceeded glucose utilization. However, after the administration of sorbitol the plasma glucose concentration decreased because glucose production decreased. After the administration of sorbitol there was no change in the metabolic clearance of glucose. This reflects the lack of a peripheral insulin effect and is consistent with the lack of any measurable C-peptide. Glucose utilization also decreased, but this decrease was less than the decrease in glucose production. Because the metabolic clearance of glucose remained unchanged, it was concluded that the change in glucose utilization was solely due to the decrease in glucose concentration. The absence of C-peptide in the plasma indicated that changes in glucose turnover were not related to any changes in endogenous plasma insulin. Furthermore, the plasma glucagon concentration increased and, hence, changes in this hormone could not account for the decrease in glucose production. Therefore, it was concluded that the sorbitol-induced decline in glucose production was due to a direct effect on hepatic metabolism.
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PMID:Studies of glucose turnover and renal function in an unusual case of hereditary fructose intolerance. 1 54

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


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