Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Asparagine synthetase (L-aspartate:ammonia ligase (AMP-forming, EC 6.3.1.1) activity in rat liver increased when the animals were put on a low casein diet. The enzyme was purified about 280-fold from the supernatant of rat liver homogenate by a procedure comprising ammonium sulfate fractionation. DEAE-Sepharose column chromatography, and Sephadex G-100 gel filtration. The optimal pH of the enzyme was in the range 7.4-7.6 with glutamine as an amide donor. The molecular weight was estimated to be approximately 110,000 by gel filtration. Chloride ion was required for the enzyme activity. The apparent Km values for L-aspartate, L-glutamine, ammonium chloride, ATP, and Cl- were calculated to be 0.76, 4.3, 10, 0.14, and 1.7 mM, respectively. The activity was inhibited by L-asparagine, nucleoside triphosphates except ATP, and sulfhydryl reagents. It has been observed that the properties of asparagine synthetase from rat liver are not so different from those of tumors such as Novikoff hepatoma and RADA 1.
 ...
PMID:Purification and properties of asparagine synthetase from rat liver. 2 63

The clinical and biochemical response to 25-hydroxycholecalciferol (25-HCC) and vitamin D3, 150 microgram/day for 20 days has been compared in infants aged 3--18 months with nutritional rickets. The infants were allocated at random to Group I (11 infants) treated with 25HCC and Group II (9 infants) treated with vitamin D3. In addition 15 matched control children without rickets were allocated to Group III and received 25-HCC 75 microgram/day for 20 days. Preliminary studies showed that plasma calcium, phosphorus, alkaline phosphatase and urine pH all differed significantly between the rachitic and control groups. The biochemical parameters in both groups of rachitic children became normal after treatment with the exception of plasma alkaline phosphatase which remained elevated. The control group showed a significant increase in plasma and urine calcium values in spite of the low dose of 25-HCC. The findings suggest that 25-HCC is as effective as vitamin D3 in the treatment of rickets but did not demonstrate any therapeutic advantage.
 ...
PMID:Therapeutic and collateral effects of 25-hydroxycholecalciferol in vitamin D deficiency. 2 50

Analogs of cyclic AMP elevate the synthesis of tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase; EC 2.6.1.5) in cultured hepatoma cells and rat liver at a post-transcriptional level but have no discernible effect on total soluble protein synthesis. In order to determine whether cyclic AMP exerts its effect on a step before or after initiation of the synthesis of this enzyme, we have analyzed the ribosomal transit times for both the aminotransferase and total soluble protein in hepatoma cells incubated in the presence or absence of N(6),O(2)'-dibutyryl cyclic AMP. The time required for one ribosome to translate one subunit of the "average" soluble protein (transit time) was about 2 min in cells incubated with or without the cyclic AMP analog. In contrast, the transit time for tyrosine aminotransferase was found to be reduced from 5-8 min under basal conditions to as low as 45 sec after exposure to dibutyryl cyclic AMP. Although the degree of effect varied from experiment to experiment, the relative rate of aminotransferase nascent chain elongation was found to be proportional to the stimulation of its activity. In contrast, dexamethasone did not alter the rate of aminotransferase elongation even though it elevated enzyme activity between 5- and 10-fold. These data are consistent with the hypothesis that induction of tyrosine aminotransferase with cyclic AMP analogs occurs by stimulation of the rate at which ribosomes translate pre-existing mRNA in contrast to adrenal steroids which act by increasing the level of translatable mRNA coding for this enzyme.
 ...
PMID:Evidence for acceleration of the rate of elongation of tyrosine aminotransferase nascent chains by dibutyryl cyclic AMP. 2 12

Cytoplasmic tyrosine aminotransferase (L-tyrosine: 2-oxoglutarate aminotransferase, EC2.6.1.5) was partially purified from host liver and Morris hepatoma No. 7777 grown in pyridoxine depleted rats. The animals were sacrificed six hours following the intraperitoneal administration of hydrocortisone hemisuccinate. Enzyme preparations were subsequently resolved by electrophoresis on polyacrylamide gels. Enzyme activity was detected histochemically in situ on the gels. Six and at least three enzymatically active protein peaks were detected in host liver and the hepatoma, respectively, by this method.
 ...
PMID:Expression of hormonally induced tyrosine aminotransferase in host liver and Morris hepatoma No. 7777 during cofactor depletion. 2 38

Alkaline phosphatase was purified from plasma membranes of rat ascites hepatoma AH-130, the homogenate of which had 50-fold higher specific activity than that found in the liver homogenate. The presence of Triton X-100, 0.5%, was essential to avoid its aggregation and to stabilize its activity. The purified enzyme, a glycoprotien, was homogeneous in polyacrylamide gel electrophoresis. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate indicated a protein molecular weight of 140,000. The addition of beta-mercaptoethanol caused the dissociation of the alkaline phosphatase into two subunits of identical molecular weight, 72,000. Isoelectric focusing revealed that the pI of this enzyme is 4.7. The pH optimum for the purified enzyme was 10.5 or higher with p-nitrophenylphosphate, and slightly lower pH values (pH 9.5--10.2) were obtained when other substrates were used. Of the substrates tested, p-nitrophenylphosphate (Km-0.3 mM) was most rapidly hydrolyzed. Vmax values of other substrates relative to that of p-nitrophenylphosphate were as follows; beta-glycerophosphate, 76%; 5'-TMP, 82%; 5'-AMP, 62%; 5'-IMP, 43%; glucose-6-phosphate, 39%; ADP, 36% and ATP, 15%. More than 90% of the activity of the purified enzyme was irreversibly lost when it was heated at 55 degrees C for 30 min, or exposed either to 10 mM beta-mercaptoethanol for 10 min to 3 M urea for 30 min, or to an acidic pH below pH 5.0 for 2 h. Of the effects by divalent cations, Mg2+ activated the enzyme by 20% whereas Zn2+ strongly inhibited it by 95% at 0.5 mM. EDTA at higher than 1 mM inactivated the enzyme irreversibly, although the effect of EDTA at lower than 0.1 mM was reversible by the addition of divalent cations, particularly by Mg2+. The enzyme was most strongly inhibited by L-histidine among the amino acids tested, and also strongly inhibited by imidazole. These results suggest that alkaline phosphatase of rat hepatoma AH-130 is very similar to that of rat liver in most of the properties reported so far.
 ...
PMID:Purification and characterization of alkaline phosphatase from plasma membranes of rat ascites hepatoma. 2 78

Tyrosine adminotransferase (EC 2.6.1.5) has been found to be phosphorylated in intact rat hepatoma cells in culture. Incorporation of [32p]i into the enzyme is rapid and is exclusively found as phosphoserine. Cycloheximide treatment reduced phosphorylation of the aminotransferase only slightly and in the presence of three different inducers of this enzyme, dexamethasone, insulin, and dibutyryl cyclic AMP, [32P]I incorporation was increased. It is concluded that [32p]i incorporation into this enzyme probably reflects turnover of phosphate groups associated with pre-existing enzyme molecules catalyzed by a cyclic AMP-independent protein kinase.
 ...
PMID:Relationship between phosphorylation of tyrosine aminotransferase and regulation of its synthesis by cyclic AMP and hormones. 2 2

trans-Aziridine-2,3-dicarboxylic ester was used to prepare the required beta-chlorohydroxamic acid used in the synthesis of the title compound. The trans configuration of the asparagine analogue was established by hydrogenolysis to erythro-beta-hydroxyasparagine amide. Neither the title compound nor the intermediate aziridinehydroxamic acid (8) showed significant activity against the L1210 and P-388 tumors. The title compound was inactive as an inhibitor of asparagine synthetase from Novikoff hepatoma and did not inhibit the growth of some 25 bacteria and fungi.
 ...
PMID:5-Carboxamido-4-amino-3-isoxazolidone, and asparagine analogue. 2 38

In certain lines of hepatoma tissue culture (HTC) cells, glutamine synthetase (EC 6.3.1.2) specific activity is increased 2.5- to 3-fold by the addition of glucocorticoids to the growth media. Actinomycin D blocks both the induction and deinduction of glutamine synthetase by glucocorticoids, suggesting a requirement of RNA synthesis for both processes. Using an antiserum raised against purified rat liver glutamine synthetase, we have precipitated radiolabeled glutamine synthetase from HTC cells. Electrophoresis of the immunoprecipitates on sodium didecyl sulfate-acrylamide gels isolates the subunit of glutamine synthetase and permits the radioactivity in the glutamine synthetase band to be quantitated. Using this technique, we have investigated the effect of dexamethasone, a synthetic glucocorticoid, on the rates of synthesis and degradation of glutamine synthetase. Dexamethasone (10(-7) M) increases the rate of synthesis of glutamine synthetase 2- to 3-fold but has no effect on the rate of glutamine synthetase degradation. The rates of total cell protein synthesis and degradation are not significantly affected by dexamethasone. The presence of actinomycin D at the time of removal of dexamethasone from induced cells prevents the fall in the induced rate of synthesis of glutamine synthetase normally seen when the inhibitor is removed from the culture medium. The regulation of glutamine synthetase by dexamethasone has been compared to the regulation of another dexamethasone-inducible enzyme in HTC cells, tyrosine aminotransferase, and been found to be similar in all parameters studied.
 ...
PMID:Regulation of glutamine synthetase by dexamethasone in hepatoma tissue culture cells. 2 25

gamma-Glutamyltranspeptidase was purified 600-fold from Morris hepatoma 5123D by six-step procedure. Its apparent molecular weight estimated by centrifugation in sucrose gradient with Triton X-100 amounts to 108 000. Some dipeptides particularly glycylglycine and several amino acids considerably increase the enzyme activity but L-serine with borate decreases it. Usually transfer activity of the enzyme towards gamma-L-glutamyl substrates was much higher than hydrolytic. The best substrate for the hepatoma enzyme is reduced glutathione.
 ...
PMID:Isolation and properties of gamma-glutamyltranspeptidase from Morris hepatoma 5123D. 2 88

Adenylate cyclase activity as well as intracellular content of sAMP were decreased 2.5-4-fold, as compared with normal state, in plasmatic membranes (PM) of hepatoma 22 and of Ehrlich ascites carcinoma--the tumors characterized by high level- of malignancy. Activity of cAMP phosphodiesterase exceeded distinctly the normal value in all the tumors studied. In less malignant hepatoma 48 the adenylate cyclase activity and content of cAMP were similar to those found in normal liver cells. The guanylate cyclase activity did not differ markedly from values found in normal liver cells in PM of all the tumors studied and in liver tissue of the tumor-bearing animals. Distinct alterations were not found in content of cGMP in the tumors, except of hepatomas 60 and 22, in which the nucleotide level exceeded 2-fold the normal value. The ratio cAMP/cGMP was decreased in the most malignant tumors. At the same time, the ratio was distinctly elevated in tumors with the middle level of malignancy (hepatomas 60 and 61).
 ...
PMID:[Concentration of cyclic nucleotides, activity of adenylate cyclase, 3',5'-AMP phosphodiesterase and guanylate cyclase in plasma membranes from liver and hepatomas of different degrees of malignancy]. 3 Feb 12


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