Purification and properties of thymidine kinase from regenerating rat liver

Kizer, Donald E.; Holman, Leroy

doi:10.1016/0005-2744(74)90217-4

Cited by 28 publications

(12 citation statements)

References 17 publications

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“…5b) were interpreted in this light with thymidine kinase showing a shift from negative to positive substrate cooperativity at a critical thymidine concentration (5 pM). Studies with purified thymidine kinase are in keeping with this interpretation (22,23), and purified deoxycytidine kinase shows similar properties with respect to deoxycytidine (24). It is possible that the two phases of relief by thymidine (Fig.…”

Section: Biphasic Reliefby Thymidine Of6nhibifion By Fdllrdmentioning

confidence: 64%

Isotope-dilution studies of the effects of 5-fluorodeoxyuridine and hydroxyurea on the incorporation of deoxycytidine and thymidine by cultured thymus cells

Scott¹,

Forsdyke²

1976

Can. J. Biochem.

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From experimentally induced changes in the slope (Vmax) and intercept (pool) of isotope-dilution plots inferences may be drawn on the position and regulation of rate-limiting steps affecting the incorporation of pyrimidine deoxynucleosides by intact cells. 5-Fluorodeoxyuridine (FdUrd; 1 μM) reduced the Vmax of radioactive labelling with deoxy[5-3H]cytidine; this was reversed by thymidine (19 μM) suggesting that FdUrd makes the concentration of deoxythymidine triphosphate (dTTP) rate-limiting for DNA synthesis. With deoxy[U-14C]cytidine the reversal of FdUrd inhibition by thymidine was only partial; this was in keeping with (i) deoxy[U-14C]cytidine labelling both cytosine and thymine in DNA, and (ii) a continuing inhibition of thymidylate synthetase by FdUrd in the presence of thymidine (19 μM).The deoxycytidine competitor pool was increased by cytidine (10–50 μM) and decreased by (i) thymidine (19 μM), (ii) hydroxyurea (50 μM) and (iii) deoxycytidine (12 μM, in the presence of FdUrd). It is suggested that these pool-decreasing agents, or their derivatives (e.g., dTTP), inhibit ribonucleotide reductase and hence prevent the entry of pyrimidine ribonucleotide derivatives into the deoxycytidine competitor pool; because of this pool decrease, radioactive labelling with deoxy[5-3H]cytidine was enhanced by thymidine (19 μM) and hydroxyurea (50 μM). However, at the latter hydroxyurea concentration, labelling with [Me-3H]thymidine was inhibited, due to a decrease in the Vmax of the rate-limiting step for thymidine incorporation (probably thymidine kinase). This sensitivity of labelling with [Me-3H]thymidine to inhibition by hydroxyurea (50 μM) was reduced by adding FdUrd to prevent the accumulation of dTTP. At high hydroxyurea concentrations (0.1–1.0 mM), labelling with deoxy[5-3H]cytidine was also inhibited, due to a decrease in Vmax of the rate-limiting step, which was probably at the level of DNA polymerase.The results suggest that hydroxyurea inhibits DNA synthesis by making the concentration of purine deoxynucleotides rate-limiting. Pyrimidine deoxynucleotides are formed in sufficient quantities from deoxycytidine by way of salvage pathways. Indeed, dTTP accumulates and inhibits thymidine kinase, thus amplifying the inhibitory effect of hydroxyurea on labelling with [Me-3 H]thymidine.

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Section: Biphasic Reliefby Thymidine Of6nhibifion By Fdllrdmentioning

confidence: 64%

Isotope-dilution studies of the effects of 5-fluorodeoxyuridine and hydroxyurea on the incorporation of deoxycytidine and thymidine by cultured thymus cells

Scott¹,

Forsdyke²

1976

Can. J. Biochem.

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“…15 Ornithine decarboxylase, the initial enzyme in polyamine synthesis, is induced prior to organ growth and proliferation and is considered to be essential for regeneration. 18,19 Thymidine kinase, the enzyme that phosphorylates thymidine prior to its incorporation into deoxyribonucleic acid, is also induced in proliferating tissue 20,21 and has been used widely as a biochemical index of regeneration. 13 Both ornithine decarboxylase activity at 6 h and hepatic thymidine kinase activity at 48 h after partial hepatectomy were greater in the animals having had a prior partial portal vein ligation procedure than in those without this procedure.…”

Section: Discussionmentioning

confidence: 99%

Effect of Partial Portal Vein Ligation on Hepatic Regeneration

Kahn

Kajani

Zeng

et al. 1988

Journal of Investigative Surgery

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To evaluate the effect of portal hypertension and diminished portal venous blood flow to the liver on hepatic regeneration, male rats were subjected to partial portal vein ligation and subsequently to a two-thirds partial hepatectomy. The levels of ornithine decarboxylase activity at 6 h after partial hepatectomy were greater (p < 0.001) in the rats with prior partial portal vein ligation than in those without portal hypertension. The rats with prior partial portal vein ligation also had greater (p < 0.005) levels of thymidine kinase activity at 48 h after partial hepatectomy than did those without portal hypertension. Hepatic sex hormone receptor activity was not affected by prior partial portal vein ligation either before or after partial hepatectomy. The reductions in both estrogen and androgen receptor activity observed in the hepatic cytosol after partial hepatectomy were similar to those observed in control animals. These data indicate that animals with portal hypertension having a diminished hepatic portal blood flow have a normal capacity to regenerate hepatic mass following a hepatic resection. Keywords hepatic regeneration; portal hypertension; cirrhosis; liver growth; protal blood flow The origin and nature of the factors that control hepatic regeneration remain unresolved. Portal blood has been shown to be hepatotrophic as compared to peripheral blood. 1 However, controversy continues to surround the relative importance of the qualitative changes (hormonal factors) and the quantitative changes (blood flow parameters) in portal blood that occur after partial hepatectomy as they relate to the hepatic regeneration that occurs after a partial hepatic resection. 1-8 The pancreatic hormones, insulin and glucagon, have been shown to modulate, at least in part, the regenerative response that occurs after partial hepatectomy. 1-5 These data, however, do not negate an important role for hepatic blood flow, particularly portal venous blood flow, in the regulation of hepatic regeneration following partial hepatectomy. [6][7][8] The role of hepatic blood flow in modulating liver regeneration was first suggested by the observation that hepatic atrophy occurs after an Eck fistula (end-to-side portal caval shunt). 6 This hepatic atrophy was thought to be the result of a reduced hepatic blood flow,

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“…The inhibitory factor in the cell extracts of these microbes may be an active inhibitor directed against TK itself (Okazaki & Kornberg, 19646;Kizer & Holman, 1974;Madhav et al, 1980), TMP phosphatase, or TdRdecomposing enzymes such as TdR phosphorylase. The inhibitor may be an ATP phosphatase which stimulates TdR degradation in the reaction mixture by lowering the concentration of ATP (this antagonizes TdR degradation) as reported by Grivell & Jackson (1968).…”

Section: Discussionmentioning

confidence: 99%

“…In any case, the inhibitory activity in the cell extracts of these organisms is too low to cause a complete lack of TK activity. Since the cell extracts were stored at -20 or -80 "C until use and the reaction mixture contained a sufficient amount of bovine serum albumin as TK stabilizer (Okazaki & Kornberg, 1 9 6 4~; Kizer & Holman, 1974), the possibility can be excluded that the TK of these organisms was inactivated during their storage or enzyme assay incubation, although TK of E. coli and mammalian origin is unstable (Okazaki & Kornberg, 1964a;Hopgood & Ballard, 1974;Kizer & Holman, 1974;Ellims & Van Der Weyden, 1980). The present findings strongly suggest an inherent deficiency of TK in the actinomycetes (Nocardia and Streptomyces) and related organisms (Mycobacterium, Rhodococcus and Corynebacterium).…”

Section: Discussionmentioning

confidence: 99%

“…Measurement of TK activity of cell extracts was done according to the method of Kizer & Holman (1974) with modifications. Briefly, the reaction mixture (0.2 ml) consisted of 62.5 mM-Tris/HCl (pH 8.0), 10 mM-ATP, 10 mM-MgCI,, 2.5 mM-NaF, 1 mM-DTT, 250 pg bovine serum albumin ml-(as a stabilizer of TK) (Okazaki & Kornberg, 1964a), 1 0 p~-[~H ] T d R (500 Ci mol-I), and cell extract (50 or 1OOp1).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thymidine Kinase of Bacteria: Activity of the Enzyme in Actinomycetes and Related Organisms

Saito

Tomioka

1984

Microbiology

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Various micro-organisms were studied for their thymidine kinase (adenosine 5'-triphosphate : thymidine 5'-phosphotransferase, EC 2.7.1.21) (TK) activity. The sonicated cell extract of Escherichia coli K12 had a TK activity of 35-66 pmol thymidine monophosphate formed min -(mg protein)-l . The cell extracts of Salmonella typhimurium and Klebsiella pneumoniae showed a markedly higher (5-to 11-fold) TK activity. Somewhat lower but significant TK activity was detected in the cell extracts of Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis and Proteus mzrabilis. In contrast, weak TK activity, if any, was detected in the cell extracts of Pseudomonas aeruginosa. This was also the case with respect to the cell extracts of various actinomycetes (such as Nocardia and Streptomyces) and related organisms (such as Corynebacterium, Mycobacteriurn and Rhodococcus).

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Purification and properties of thymidine kinase from regenerating rat liver

Cited by 28 publications

References 17 publications

Isotope-dilution studies of the effects of 5-fluorodeoxyuridine and hydroxyurea on the incorporation of deoxycytidine and thymidine by cultured thymus cells

Isotope-dilution studies of the effects of 5-fluorodeoxyuridine and hydroxyurea on the incorporation of deoxycytidine and thymidine by cultured thymus cells

Effect of Partial Portal Vein Ligation on Hepatic Regeneration

Thymidine Kinase of Bacteria: Activity of the Enzyme in Actinomycetes and Related Organisms

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