Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.1.21 (thymidine kinase)
7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of vaccinia virus-induced thymidine kinase is normally arrested several hours after infection. In thymidine kinase-deficient LM cells infected with IHD strain of vaccinia virus, arrest occurs whether or not viral DNA synthesis is inhibited. With virus inactivated by UV irradiation, enzyme synthesis takes place, but arrest is abolished. It is suggested that an early viral genetic function is responsible for the cessation of thymidine kinase synthesis.
...
PMID:Control of thymidine kinase synthesis in IHD vaccinia virus-infected thymidine kinase-deficient LM cells. 12 55

The effects of 5-fluorodeoxyuridine and methotrexate on [3H]thymidine and 32P labeling of mtDNA were studied in two lines of mouse L-cells. LMTK- cells, which lack the major cellular thymidine kinase (EC 2.7.1.21) but contain a genetically distinct mitochondrial enzyme, were compared to LA9 cells, which contain both thymidine kinase activities. LMTK- cells were resistant to 5-flurodeoxyuridine by a factor of 200 in comparison to LA9 cells. In both cells lines appropriate drug treatment increased utilization of exogenous thymidine for mtDNA synthesis. The maximum enhancement was 10- to 12-fold for LA9 cells and approximately 20-fold for LMTK- cells when treated with 10 muM methotrexate. The rates of mtDNA and nuclear DNA synthesis during drug treatment were analyzed with 32P labeling and 5-bromo-2'-deoxyuridine density labeling experiments. Synthesis of both mtDNA and nuclear DNA were strongly inhibited by drug treatment of either LA9 or LMTK- cells in the absence of exogenous thymidine. The rate of mtDNA synthesis substantially exceeded that of nuclear DNA in LA9 cells treated with 4 muM 5-fluorodeoxyuridine and less than 5 muM thymidine. Both synthetic rates approached those of untreated LA9 control cultures if 20 muM thymidine was present during 5-fluorodeoxyuridine treatment. In contrast, in LMTK- cells treated with 10 muM methotrexate and 20 muM thymidine, mtDNA synthesis continued at 50 to 60% of the control rate for at least 10 hours while nuclear DNA synthesis was 96% inhibited. Synthesis of mtDNA mass-labeled in both strands with 5-bromouracil occurred when LMTK- cells were incubated for 30 hours with 10 muM methotrexate and 20 muM 5-bromodeoxyuridine. These results indicate that mtDNA synthesis is resistant to a limitation of the thymidine triphosphate supply and is not strictly dependent upon concomitant nuclear DNA synthesis in these cells.
...
PMID:Thymidylate nucleotide supply for mitochondrial DNA synthesis in mouse L-cells. Effect of 5-fluorodeoxyuridine and methotrexate in thymidine kinase plus and thymidine kinase minus cells. 13 1

The influx of 1.0 muM 5-fluoro[6-3H]deoxyuridine (5F[6-3H]dUrd) into L5178Y mouse leukemia cells followed a linear function with time from 2 to 10 min. Ammonium 5-bromodeoxyuridine 5'-methylphosphonate (BrdUrd-OPO2Me) inhibited the membrane transport of 5F[6-3H]dUrd into L5178Y cells. Influx of 5F[6-3H]dUrd into inhibited cells was observed from zero to 3 min; after 3 min the net rate of 5F[6-3H]dUrd uptake into the cells treated with 18 muM BrdUrd-OPO2Me was almost zero. The cellular uptake of 2'-deoxy[6-3H]uridine or 5-bromo[6-3H]deoxyuridine was inhibited by BrdUrd-OPO2Me. The L5178Y cells were grown for 96 hr in a medium that contained tritium-labeled BruDur-OPO2Me. An analysis of the labeled products in the growth medium showed that the ester linkage is not cleaved to separate the [3H]methylphosphonate group and the nucleoside moiety of BrdUrd-OPO2[3H]Me. The activity of thymidine kinase in a cell-free preparation from L5178Y cells was demonstrated. Although 37 muM 5-bromo-2'deoxyuridine produced an inhibition of approximately 45% in kinase activity, BrdUrd-OPO2Me had no effect on enzyme activity. The results indicate that BrdUrd-OPO2Me is an inhibitor of the cell membrane transport of the 5-fluoro and 5-bromo derivatives of 2'-deoxy[6-3H]uridine.
...
PMID:Inhibition of membrane transport of 5-fluoro[6-3H]deoxyuridine into L5178Y mouse leukemia cells. 13 41

Measurements of the deoxyribonucleoside triphosphate (dNTP) contents, the [14C] thymidine and deoxyuridine incorporation and the "key enzymes" of the thymidine triphosphate (dTTP) synthesis, thymidine kinase and ribonucleotide reductase, in diploid Ehrlich-ascites carcinoma, in Yoshida sarcoma-ascites cells and to a smaller extent in surgically removed malignant human tumours show 1. A distinctly increased dTTP content compared with the remaining dNTP is not a characteristic of tumour cells generally but a peculiarity of sarcoma and a sign of differentiation of a malignant tumour. 2. With simultaneous linear deoxyribonucleoside incorporation the dTTP content and the mix-proportion of [14C] dTTP to total dTTP in ascites tumour cells in short-term in-vitro incubation (120 min) remain constant. 3. Thymidine addition to the medium leads to a distinct rise of dTTP concentration even at a dosage of 3 X 10(-5) M. 4. The dNTP contents of ascites tumour cells are within the range of the endproduct-inhibiting concentrations of thymidine kinase and ribonucleotide reductase.
...
PMID:[Studies on the thymidine-triphosphate synthesis in malignant tumors. I. Effects of thymidine on deoxyribonucleoside triphosphate pools and deoxyribonucleic acid synthesis (author's transl)]. 13 36

Measurements of the deoxyribonucleoside triphosphate (dNTP) contents, the [14C] thymidine and deoxyuridine incorporation and the "key enzymes" of the thymidine triphosphate (dTTP) synthesis, thymidine kinase and ribonucleotide reductase, in diploid Ehrlich-ascites carcinoma, under the application of hyperthermia, vitamin K and cytocidal agents show: The effect of hyperthermia and menadion (the basic substance of the K vitamins) on the above parameters of dNTP synthesis can explain the labile effects of hyperthemia and vitamin K therapy on cancer growth. Alterations of the dNTP concentrations and demonstrable or absent inhibition of the ribonucleotide reduction with application of fluoruracil, amethopterine, cytosine arabinoside, hydroxyurea, trisethylen iminobenzochinone and daunomycin confirm and supplement our knowledge of the cytostatic action mechanism of these substances. They show moreover by the example of fluoruracil and amethopterine medication that the dTTP concentration estimation after in-vitro incubation of tumour cells with the addition of FU or methotrexat is a better measurement of the therapeutic in-vivo responsiveness of malignant tumours than the previously performed test methods.
...
PMID:[Studies on the thymidine-triphosphate synthesis in malignant tumors. II. Effect of hyperthermia, Vitamin K and Cytotoxic agents (author's transl)]. 13 37

A line of HeLa cells resistant to 5-bromo-2'-deoxyuridine (BUdR) was established by continuous culture in growth medium containing BUdR; during the selection period, BUdR concentrations, initially 15 micrometer, were gradually increased to 100 micrometer. Cells of a clone (HeLa/B5) established from this line were also resistant to 5-fluoro-2'-deoxyuridine (FUdR), but not to the free base, 5-fluorouracil. Although extracts of HeLa/B5 cells exhibited levels of thymidine kinase activity comparable to those of parental cells, rates of uptake of BUdR, FUdR, and thymidine into intact cells were much reduced. The kinetics of uptake of uridine and adenosine, nucleosides which appear to be transported independently of thymidine in HeLa cells, were similar for HeLa/B5 and the parental line (HeLa/O). Relative to thymidine uptake by HeLa/O cells, that by HeLa/B5 cells was distinctly less sensitive to nitrobenzylthioinosine (NBMPR), a specific inhibitor of nucleoside transport in various types of animal cells. Despite this difference in NBMPR sensitivity, both cell lines possessed the same number of high affinity NBMPR binding sites per mg cell protein. The altered kinetics of thymidine uptake and the NBMPR insensitivity of that function in HeLA/B5 cells suggest that resistance to BUdR is due to an altered thymidine transport mechanism.
...
PMID:Defective transport of thymidine by cultured cells resistant to 5-bromodeoxyuridine. 14 16

Mouse fibroblasts resistant to the drug rutamycin were isolated by selectively introducing BrdUrd into the mitochondrial genome of a line of mouse fibroblasts (clone 1 D) lacking a cytoplasmic thymidine kinase enzyme. The ATPase (ATP phosphohydrolase; EC 3.6.1.3) activity of mitochondria isolated from these cells was resistant to rutamycin. The rutamycin-resistant mutants were enucleated with cytochalasin B and fused with mouse A 9 cells resistant to 8-azaguanine and sensitive to rutamycin. Cytoplasmic hybrids, or cybrids, were selected as cells resistant to rutamycin and 8-azaguanine, and appeared at a high frequency. Other fusions between rutamycin-resistant nucleated cells and A 9 produced colonies at a much lower frequency. Finally, fusions between enucleated clone 1 D cells and A 9 cells produced no rutamycin-resistant colonies. These results indicate that rutamycin resistance is a cytoplasmically inherited characteristic in this cell line.
...
PMID:Cytoplasmic inheritance of rutamycin resistance in mouse fibroblasts. 14 79

Methods have been developed to assay several aspects of 5-fluoro-2'-deoxyuridine and 5-fluorouracil metabolism in tissue culture cells. These methods allow measurement of (a) intracellular levels of the covalent complex formed between 5-fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP), 5,10-methylenetetrahydrofolate, and thymidylate synthetase; (b) incorporation of drug into RNA; and (c) analysis of drug metabolites. The methods were developed using radioactively labeled drugs, but they should be adaptable to studies using nonlabeled compounds. Sephadex G-25 chromatography or trichloroacetic acid precipitation were utilized for isolation of the macromolecular cell fraction; prior treatment of this fraction with RNase or heating at 65 degrees for 15 min resulted in selective removal of RNA or the thymidylate synthetase complex, respectively, from the precipitable fraction. Free intracellular drug metabolites present in the acid-soluble fraction were analyzed by high-pressure liquid chromatography. Following incubation of HTC cells with [6-3H]-5-fluoro-2'-deoxyuridine, a radioactive macromolecule was isolated and identified as a FdUMP-5,10-methylenetetrahydrofolate-thymidylate synthetase complex. Intracellular formation of this complex was shown to be dependent on the presence of the enzyme thymidine kinase. Dissociation of the complex in vivo was first order with a t1/2 of 6.2 hr; in contrast, a t1/2 of 2 hr was determined for dissociation of the complex in cytosol. Incubation of L1210 cells with [6-3H]-5-fluorouracil for 22 hr resulted in formation of 80 fmol of FdUMP-5,10-methylenetetrahydrofolate-thymidylate synthetase complex per 10(6) cells, as compared with 400 fmol of drug incorporated into RNA per 10(6) cells. Intracellular FdUMP could not be detected in the acid-soluble fraction of these cells unless the cells were first heated to dissociate the complex.
...
PMID:Assay of intracellular free and macromolecular-bound metabolites of 5-fluorodeoxyuridine and 5-fluorouracil. 15 5

Intact mitochondria of Neurospora crassa incorporate deoxythymidine 5'-monophosphate (dTMP) into deoxyribonucleic acid but not the label from (methyl-3H) deoxythymidine. Mitochondrial homogenates contain deoxythymidylate kinase (EC 2.7.4.9), deoxycytidylate aminohydrolase (dCMP deaminase) (EC 3.5.4.12), and thymidylate synthetase (EC 2.1.1b), but not thymidine kinase (EC 2.7.1.21) activity. dTMP kinase is loosely bound to the mitochondrial membrane and is solubilized by 0.4 M KCl in mitochondrial homogenates, the dCMP aminohydrolase deaminase) is bound to the inner membrane and is not solubilized by 0.4 M KCl. dTMP synthetase activity is found in the 2,000 times g particulate fractions by homogenization of mitochondria in 0.4 M KCl. The dCMP deaminase activity found in the particulate fraction of the inner membrane is efficiently regulated by the products of the pathway: deoxycytidine 5'-triphosphate activates whereas deoxythymidine 5'-triphosphate inhibits, as found for the soluble enzyme from other sources. These data indicate that mitochondria of N. crassa contain specific enzymes for the biosynthesis of deoxythymidine triphosphate.
...
PMID:Enzymes of deoxythymidine triphosphate biosynthesis in Neurospora crassa mitochondria. 16 27

The kinetics of formation, the stability at 40 degrees C and the serological properties of thymidine kinase and deoxycytidine kinase activities induced by herpes simplex virus have been examined. The results are consistent with the hypothesis that both activities are carried on the same molecule-a deoxypyrimidine kinase. Mutants deficient in deoxypyrimidine kinase have been used to produce, by absorption of general antisera, deoxypyrimidine kinase-specific antisera. Using immunoprecipitation and SDS-polyacrylamide gel electrophoresis, only one size of polypeptide (mol. wt. 42400 plus or minus 200) has been found, constituting the type 2 enzyme. This is close to published values for the type i enzyme but co-electrophoresis demonstrated that the polypeptide of the type i enzyme was slightly bigger.
...
PMID:Deoxypyrimidine kinases of herpes simplex viruses types 1 and 2: comparison of serological and structural properties. 16 87


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

---