Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rate of DNA synthesis is exponentially growing cells was determined by isotopedilution analysis of the incorporation of [me-3H]thymidine. Thymidine concentrations greater than 7 micrometer were used so that the rate-limiting step governing incorporation would be at the level of DNA polymerase rather than at the level of thymidine kinase [Sjostrom & Forsdyke (1974) Biochem. J. 138, 253-262]. In early exponential phase the rate determined by isotope-dilution analysis closely correlated with the rates calculated either from growth curves or from known cell-cycle parameters. However, in late-exponential phase the rate calculated from the growth curve was less than that determined by isotope-dilution analysis. We conclude that, under certain conditions, the pool-corrected rate of incorporation of [me-3H]thymidine, as determined by isotope-dilution analysis, can accurately reflect the rate of DNA synthesis. Discrepancies between the observed rate of DNA synthesis and increase in cell number could reflect an exponential degeneration of post-S-phase cells.
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PMID:The rate of deoxyribonucleic acid synthesis by cultured Chinese-hamster ovary cells. An application of isotope-dilution analysis. 34 2

Thymidine kinase and DNA polymerase enzyme activities were measured in epididymal adipose tissue from rats of 12 to 182 days of age. Both enzymes showed highest specific activity during the suckling period; by 35 days of age both thymidine kinase and DNA polymerase enzyme activities had decreased to stable lower levels. The activities of the two proliferative enzymes resembled the pattern of [3H]thymidine incorporation into preadipocytes shown by Greenwood and Hirsch (1) and the data support the concept that a pool of preadipocytes develops during the first 4 to 5 weeks postnatally. Further, the thymidine kinase and DNA polymerase enzyme activities were correlated with the rate of DNA accretion in the preadipocyte fraction of the tissue. Since thymidine kinase activity can be measured in 20 to 40 mg of tissue. Since thymidine kinase activity can be measured in 20 to 40 mg of tissue, the technique can be adapted for measurement of enzyme levels in human or animal biopsy samples when radio-isotope studies are not advisable or only small quantities of tissue are available.
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PMID:Thymidine kinase and DNA polymerase activity during postnatal growth of the epididymal fat pad. 43 Feb 14

During development of the rat anterior pituitary gland (APG) there is a fall in DNA replication which is accompanied by a decline in the activity of the soluble DNA polymerase and of an endonuclease. This latter enzyme is capable of activating the DNA template for the DNA polymerase assay. Sulpiride sulfate, a drug known to produce prolactin release from the APG, increases thymidine incorporation in the APG 20 h after the injection. This drug also enhances the activity of the soluble DNA polymerase while that of the endonuclease and thymidine kinase does not change. The results suggest that the intracellular prolactin content regulates DNA replication in mammotrophs and that the soluble DNA polymerase plays an important role in this regulation.
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PMID:DNA synthesis in the pituitary gland of the rat. Effect of sulpiride and postnatal maturation. 47 Nov 96

In vaccinia virus infected cells the appearance of a late enzyme RNA polymerase was prevented by MPB, an inhibitor of nucleolar RNA synthesis, although inductions of the early enzymes thymidine kinase and DNA polymerase were not affected. It is inferred the nucleoli may be involved in the replication of vaccinia virus.
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PMID:Failure of poxvirus replication in the presence of an inhibitor of nucleolar RNA synthesis. 85 97

Regenerating rat liver was used as a semisynchronous system in which to investigate the effects of 6-thioguanine on biochemical processes occurring in discrete phases of the cell cycle. 6-Thioguanine inhibited the first wave of DNA biosynthesis in regenerating rat liver. This effect appeared to be the result of a decrease, caused by 6-thioguanine, in the induction of several enzyme activities (i.e., thymidine kinase, deoxycytidylate deaminase, cytidine diphosphate reductase, and DNA polymerase) necessary for the initiation of DNA replication in regenerating liver. There was a fairly short period during which 6-thioguanine could be given to rats to accomplish the inhibition of the appearance of the induced activities of these enzymes; this period corresponded to the time just before enzyme induction. The inhibition of the induced synthesis of this group of enzymes occurred in the presence of an intact translational apparatus and intact polysomes and in the absence of interference with the incorporation of radioactive leucine and tyrosine into total protein of liver. Synthesis of polyadenylate-containing RNA was depressed in 6-thioguanine-treated rats, whereas the synthesis of polyadenylate-lacking RNA was unaffected. It is suggested that the inhibition of the synthesis of polyadenylate-containing RNA by 6-thioguanine is at least in part responsible for the observed decrease in induced enzyme activities and the resulting interference with DNA replication.
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PMID:Effects of 6-thioguanine on macromolecular events in regenerating rat liver. 87 Jan 91

Treatment with methylglyoxal bis(guanylhydrazone), a specific inhibitor of S-adenosylmethionine decarboxylase (EC 4.1.1.50), suppressed the phytohemagglutinin-induction of [3H]thymidine uptake by guinea pig lymphocytes. The kinetics of [3H]thymidine uptake revealed that the Km value for thymidine was not changed, but the V value was markedly lowered by the methylglyoxal bis(guanylhydrazone) treatment. The induction of ATP: thymidine 5'-phosphotransferase (EC 2.7.1.75) (thymidine kinase) activity by phytohemagglutinin was suppressed to about the same extent as the induction of thymidine uptake. These suppressions were dependent on the methylglyoxal bis(guanylhydrazone) doses and on duration of the methylglyoxal bis(guanylhydrazone) treatment. Analysis of [3H]thymidine labelled compounds of the acid-soluble fraction showed that conversion of thymidine to thymidine 5'-triphosphate was inhibited by the methylglyoxal bis(guanylhydrazone) treatment. DNA polymerase activity was less inhibited by the methylglyoxal bis(guanylhydrazone) treatment in comparison with the methylglyoxal bis(guanylhydrazone) inhibition of thymidine uptake by whole cells. These results strongly suggested that blocking of polyamine accumulation by the methylglyoxal bis(guanylhydrazone) treatment influenced phytohemagglutinin induction of thymidine phosphorylation, resulting in a decrease of thymidine incorporation into DNA.
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PMID:Suppression of phytohemagglutinin-induction of thymidine uptake in guinea pig lymphocytes by methylglyoxal bis(guanylhydrazone) treatment. 91 40

Enzymes of DNA synthesis, thymidine kinase (ATP-thymidine-5'-phospho-transferase, EC 2.7.1.21), DNA polymerase (EC 2.7.7.7) and nuclease activities were investigated in isolated purified nuclei of swine aorta. Thymidine kinase which is detectable in these nuclei can be stimulated by the addition of phospholipase C. DNA polymerase activity of isolated nuclei is strongly dependent on addition of an exogenous template; the preferred template is activated DNA. The activity in the absence of an added template is very low except when labelled dCTP is used as the precursor. This incorporation of labelled dCTP does not require the addition of the other three triphosphates, and under these conditions, dCTP seems to be incorporated into what may be a homopolymer. As with other tissues, solubilized preparations of aortic nuclei have two DNA polymerase activities which also prefer activated DNA template. There is no detectable endonuclease in aortic nuclei.
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PMID:Enzymes of DNA synthesis in isolated nuclei of swin aorta. 94 21

Although DNA polymerase-alpha (DNA nucleotidyltransferase; deoxynucleoside triphosphate: DNA deoxynucleotidyltransferase; EC 2.7.7.7) probably functions in the nucleus, it is usually found predominantly in the nonnuclear fraction of disrupted cells. We have reexamined the intracellular location of this enzyme using cytochalasin-B-induced enucleation, a technique which avoids exposure of nuclei to extra-cellular conditions during cell fractionation. In conditions where viability of separated cell parts is high and recovery is quantitative, we find greater than 85% of total DNA polymerase-alpha (and DNA polymerase-beta) activity in the nucleated cell fragments (karyoplasts), from which we conclude that the location in vivo of DNA polymerase-alpha is either nuclear or perinuclear. On the other hand, thymidine kinase (ATP: thymidine 5'-phosphotransferase, EC 5.7.1.75) is found primarily in the enucleated cell fragments (cytoplasts). The enucleation procedure used in this work should be of general use for intracellular location studies.
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PMID:Intracellular localization of mouse DNA polymerase-alpha. 106 93

During the fractionation of various enzymes concerned with DNA synthesis from the postmicrosomal supernatant fraction of various tissues, DNA polymerace [EC 2.7.7.7], thymidine kinase [EC 2.7.1.75], dTMP kinase [EC 2.7.4.9], deoxycytidine kinase [EC 2.7.1.74], and deoxycytidine monophosphokinase (dCMP kinase) [EC 2.7.4.14] were found in the pellet fraction of postmicrosomal supernatant. Further, the uridine kinase [EC 2.7.1.48] and aspartate transcarbamylase [EC 2.1.3.2] activities of postmicrosomal supernatant from various tissues were also present in this pellet fraction. The activities of DNA polymerase, thymidine kinase, uridine kinase, and aspartate transcarbamylase from normal and regenerating rat liver, and Yoshida sarcoma were higher in the pellet fraction than in the supernatant. On the other hand, the activities of dTMP kinase, dCMP kinase, and orotidine-5'-phosphate decarboxylase [EC 4.1.1.23] were lower in the pellet fraction than in the supernatant. The pellet fractions of regenerating rat liver and Yoshida sarcoma showed a remarkable incorporation of various precursors (thymidine, dTMP, deoxycytidine, and dCMP) into DNA in the presence of a suitable DNA template, ATP and all four deoxynucleoside 5'-triphosphates for DNA synthesis. Normal adult rat liver catalyzed a much smaller incorporation of all these precursors, except for dCMP.
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PMID:Intracellular distribution of various enzymes concerned with DNA synthesis from normal and regenerating rat liver, and Yoshida sarcoma. 113 86

Damage to the lung may be caused by chemicals that gain access to the alveolar zone by inhalation or via the pulmonary circulation. Several agents toxic to the lung have recently been found to bind covalently to pulmonary macromolecules or to disrupt certain metabolic reactions. However, it has also been observed that extensive chemical lung injury is not necessarily preceded by a depression of pulmonary metabolic reactions. One possible explanation for this might be that biochemical changes due to cell death are often masked and/or compensated for by changes associated with lung tissue repair. Substantial cell proliferation as a response to toxic lung damage is a common phenomenon in lung pathology. This makes it necessary to develop models that permit analysis of the biochemical events triggering and accompanying cell growth in lung. We have recently examined some aspects of cell proliferation in mouse lung. Intraperitoneal injection of the antioxidant butylated hydroxytoluene (BHT) produces within 3-5 days extensive hypertrophy, hyperplasia, and general disorganization of the cellular components of the lung. Total lung weight and total DNA per lung almost double within this time and are accompanied by proportional increases in protein and lipids. RNA accumulates at a faster rate than DNA. The changes in lung composition are accompanied by dose-dependent increases in the in vivo incorporation of thymidine into DNA and of leucine into protein. The activities of several enzymes (thymidine kinase, DNA polymerase, uridine kinase, glucose-6-phosphate dehydrogenase, and 5'-nucleotidase) increase substantially after BHT. Administration of BHT to mice seems to offer a convenient tool to study cell growth in the lungs of mice.
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PMID:Biochemical pathology of lung damage produced by chemicals. 124 36


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