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)

Four strains of herpes simplex virus (HSV) were isolated from two patients with recurrent herpes keratitis who failed to respond to 5'-iodo-2'-deoxyuridine (IDU) treatment. Two of the four isolates were highly resistant to IDU in cell culture and the other two isolates were more susceptible to IDU than an HSV-1 laboratory strain. From each patient, an IDU-resistant and an IDU-susceptible virus was isolated. All 4 isolates possessed the ability to induce the thymidine kinase (TK) activity in cell lines lacking that activity. All the isolates were type 1 HSV, since the filamentous structures, recognized as a biological marker of type 2 HSV, were not observed in infected cells.
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PMID:Analysis of herpes simplex virus isolated from patients with recurrent herpes keratitis exhibiting "treatment-resistance" to 5-iodo-2'-deoxyuridine. 4 35

Using gel filtration chromatography, we find a single peak of deoxythymidine phosphorylating activity in Chlamydomonas reinhardti. This activity has characteristics of a thymidine kinase, in that (1) it will utilize ATP (or dATP) or CTP (or dCTP) as phosphoryl donor, but not AMP or phenyl phosphate, and (2) it is inhibited by dTTP (and less so by dTDP, dUTP, and dUDP) but is unaffected by 3'-5' cyclic AMP. Partially purified chlamydomonas thymidine kinase has a pH optimum near 8.5, and a molecular weight of 80,000 to 85,000 daltons. Kinetic studies indicate a ping-pong mechanism with a Km for thymidine of 1.5 x 10(-7) moles per liter. 5-Bromo- and 5-fluorodeoxyuridine, and to a lesser degree deoxyuridine, are competitive inhibitors, but significant phosphorylation of these nucleotides could not be demonstrated in vitro by thymidine kinase. While thymidine is phosphorylated to dTMP by crude Chlamydomonas extracts, greater than 80% of the product formed by the partially purified enzyme is dTTP. Further, the gel filtration elution position of the single deoxythymidylate kinase activity present in cell extracts coincides with that of thymidine kinase. These results suggest that a multifunctional enzyme, rather than three separate phosphorylating activities, may be responsible for dTTP formation.
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PMID:Characterization of thymidine kinase and phosphorylation of deoxyribonucleosides in Chlamydomonas reinhardti. 4 38

RADA-1 cells (H-2a), a murine leukemia cell line maintained by serial transfer in histocompatible recipients expressing thymus-leukemia (TL) 1, 2, 3 antigenic determinants, resisted the cytotoxic effects of guinea pig complement (GPC) and TL antiserum. The cells expressed a lower density of TL antigens than did ASL-1 cells, another TL(+) leukemia cell line expressing the same determinants and susceptible to complement (C)-mediated lysis. Stable somatic cell hybrids of RADA-1 cells and LM(TK)- cells (H2k), a TL(minus) thymidine kinase-deficient mutant of mouse L cells, were selected in hypoxanthine-aminopterin-thymidine medium. The hybrid cells expressed the H-2 antigens of both parents and shared a hybrid karyotype. They formed TL 1, 2, 3 antigens as determined by immunofluorescence, mixed hemagglutination methods, the direct isolation of TL antigens from Nonidet P40 extracts of the cells, and the capacity of the cells to reduce by absorption the known titers of TL antiserum. These hybrid cells lost the capacity to resist lysis by TL antiserum and GPC. They were susceptible to the cytotoxic effects of TL 1, 2, 3; TL 2; OR TL 1, 3 antiserum and GPC, even though the density of TL antigens associated with the cells was approximately 25% of their resistant RADA-1 parental cells. These results indicated that the mechanism of resistance to C-mediated lysis was genetically separable from the expression of TL antigens by the cells and that the susceptibility of the cells to the cytotoxic effects of antiserum was related only in part to the density of TL antigens expressed by the cells.
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PMID:Complement sensitivity of somatic hybrids of a complement-resistant murine leukemia cell line. 5 Oct 86

Enhanced mitotic activity and stimulated DNA synthesis associated with unchanged activity of thymidine and thymidylate kinases were observed in mouse kidneys induced to proliferate by intracardiac injection of lead acetate, and in rat livers following repeated administration of 5-azacytidine. On the other hand, the enhanced thymidine kinase activity evoked by L-tryptophan given by intubation at later stages of liver regeneration was paralleled by the enhanced incorporation of thymidine into DNA only to a very small degree.
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PMID:Stimulated DNA synthesis in livers and kidneys induced to proliferate associated with unchanged thymidine and thymidylate kinase activities. 5 7

Herpes simplex virus (HSV)-related antigens have been demonstrated in the nuclei and cytoplasm of human and mouse cells biochemically transformed by ultraviolet light-irradiated HSV. This was accomplished by using peroxidase/anti-peroxidase immunological staining and indirect immunofluorescence with rabbit antisera that had high neutralizing titers against the HSV-specific thymidine kinase activity and virus infectivity. HSV-1 antisera reacted with antigens in cells biochemically transformed by type 1 HSV, but not with those of cells biochemically transformed by type 2 HSV. Similarly, HSV-2 antisera reacted with antigens in cells biochemically transformed by HSV-2, but not with those in cells biochemically transformed by HSV-1. In contrast, herpes virus-related antigens were detected in cells cytolytically infected with HSV-1 and with HSV-2 by either type 1 or type 2 HSV antisera. These observations suggest that the antigens detected in the biochemically transformed cells were a type-specific subset of the HSV-related antigens synthesized in cells undergoing productive infection by HSV-1 and HSV-2.
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PMID:Detection of herpes simplex virus-related antigens in the nuclei and cytoplasm of biochemically transformed cells with peroxidase/anti-peroxidase immunological staining and indirect immunofluorescence. 7 Dec 79

An increase of thymidine kinase [EC 2.7.1.21] activity and decrease of 5'-nucleotidase [EC 3.1.3.5] activity for dTMP were found during hormonal regeneration of the seminal vesicles by daily or single administration of testosterone propionate into mice castrated 2 weeks previously. Actinomycin D injected on day 0 of testosterone treatment completely inhibited both the increase of thymidine kinase and the decrease of 5'-nucleotidase. When injected on day 2, actinomycin D decreased thymidine kinase activity below the control level and 5'nucleotidase activity was not restored to the normal level. The activity of 5'-nucelotidase in a mixed sample, in which seminal vesicles of castrated mice and those of testosterone-treated mice were homogenized together, was intermediate between the activities determined separately. This indicates the absence of any inhibitor of 5'nucleotidase in the regenerating vesicles. Changes in total activity of 5'nucleotidase and total protein content in extracts during various treatments showed that the decrease in specific activity of 5'-nucleotidase in the first 2 days of testosterone treatment was not due to inhibition of enzyme activity but to dilution of the enzyme with other proteins which increased in content more rapidly than 5'-nucleotidase.
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PMID:Changes in enzyme activities of thymidine kinase and 5'-nucleotidase for dTMP during hormonal regeneration of seminal vesicles of mice. 7 66

Continuous monitoring of enzymes, particularly those involved in nucleic acid synthesis could be a useful means of detecting infections and abnormalities in cells in culture. Model systems using mouse (3T3), human (MRC-5) and chick embryo cells infected with RNA tumour viruses were studied. Reverse transcriptase activities were determined by the incorporation of (3H) nucleotides into synthetic primer-templates or into complementary DNA of endogenous RNA and characterised by their specificity for primer-templates dT12-18.rAn, dG12-18.rCn, dT12-18.DAn and dG10.rCmn, their requirements for metal ions and inhibition by antisera. Measurement of reverse transcriptase is a more sensitive method than the COFAL test for the detection of RAV infection of chick cells. Iododeoxyuridine, bromodeoxyuridine and dexamethasone, which can induce latent C viruses, have no effect on MRC-5 cells; no increases in reverse transcriptase were detected and no C particles were seen by electron microscopy. Solid tumours developed in immunosuppressed mice injected s/c with 3T3 and MRC-5 cells chronically infected with MLV but none formed after injection of cells or virus suspension alone. Thymidine kinase activities of WI-38 and MRC-5 cells are greatly increased by infection with CMV or transformation with SV40. Mammalian tumours and tumour cell lines also show a high specific activity of cytoplasmic thymidine kinase.
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PMID:Reverse transcriptase and thymidine kinase as markers for tumorigenicity and viral contamination of cells. 7 84

The presence of thymidine kinase has recently been reported in Tetrahymena pyriformis. The activity pattern for this enzyme was investigated during the cell cycle in both the one heat-shock per cell generation and the starvation-refeed system. Thymidine kinase was found to be a peak enzyme during S-phase in both situations. Nucleoside phosphotransferase was a continuous enzyme in the one heat-shock per cycle system, however, it closely paralleled the thymidine kinase curve during starvation and refeeding.
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PMID:Activity of thymidine kinase during the cell cycle in Tetrahymena pyriformis. 10 28

Hemocytes and non hemocytes in vitro cell lines from Periplaneta americana, have been tested for their ability to incorporate, in the presence of vitamin B 12, various nucleic acid precursors into their DNA. Evidence was shown for enhanced transformation of all ribonucleotides into deoxyribonucleotides in the presence of vitamin B 12. Moreover, in hemocyte cell lines, it was demonstrated that vitamin B 12 produced an activation of thymidine kinase activity.
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PMID:[Role of vitamin B 12 in the incorporation of ribonucleosides into the DNA of various Periplaneta americana cell lines]. 11 4

Our purpose was to determine whether phospholipase C stimulated thymidine kinase activity of regenerating rat liver. We determined effects of phospholipase C upon TMP formation by rat liver extracts prepared at 0, 12, 24, 36 and 48 hr following partial hepatectomy. Data were obtained which supported these conclusions: (a) Commercial preparations of phospholipase C contained nucleoside phosphotransferase activity; (b) phospholipase C exerted no appreciable stimulatory influence upon thymidine kinase activity of regenerating rat liver; and (c), apparent stimulation of thymidine kinase was associated with linked activities of two enzymes, viz., liver extract-ATPase activity and nucleoside phosphotransferase activity.
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PMID:Does phospholipase C stimulate thymide kinase activity of rat liver extracts prepared after partial hepatectomy. 12 59


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