Kinetic studies of the reactions catalyzed by herpes simplex virus type l-encoded thymidine and thymidylate multifunctional kinase indicate that the addition of substrates (thymidine and ATP*Mg’+, or thymidylate and ATP l Mg2+) to the enzyme is random, while release of the products (thymidylate and ADP*M8+, or thymidine diphosphate and ADP*Mg+) is ordered, with ADP.Mg2+ being released first. Th...

background: many in vitro studies suggested that choline incorporation into many types of tumors is related to cell proliferation. whether in vivo choline incorporation is related also to cell proliferation or not was my question. therefore, the aim of this pilot study was to investigate the relationship of in vivo [methyl- 14c]-choline incorporation and in vivo [methyl-3h]- thymidine incorpora...

Background: The organochlorine DDT has estrogenic activity but the mechanism underlying the estrogenic activity of this pesticide remains unclear. In the present investigation here, we studied the transcriptional effects of a synthetic organochlorine pesticide o,p’-DDT [1.1.1.-trichloro-2-(o-chlorophenyl)-2-p-chloriphenyl ethane] and its metabolite p,p'-DDE (2-2-bis(4/chlorophenyl)-1-1-di...

These studies explore the effects of an epipodophyllotoxin on the membrane transport and metabolism of thymidine in Ehrlich ascites tumor cells. Uptake of 3H after exposure of cells to [3H]-thymidine is characterized by a rapid initial velocity that approximates membrane transport followed by a slower rate of uptake that parallels the accumulation of phosphorylated derivatives of thymidine, pri...

These studies explore the effects of an epipodophyllotoxin on the membrane transport and metabolism of thymidine in Ehrlich ascites tumor cells. Uptake of 3H after exposure of cells to [3H]thymidine is characterized by a rapid initial velocity that approx imates membrane transport followed by a slower rate of uptake that parallels the accumulation of phosphorylated derivatives of thymidine, pri...

A thymidine kinase (EC 2.7.1.21) associated with mitochondria has been demonstrated in tissue culture both in wild type mouse cells and in cells which lack the cytoplasmic thymidine kinase. The mitochondrial thymidine kinase represents approximately 1% of the total cell thymidine kinase activity in wild type cells grown in culture and all of the activity of the mutant cells. The mitochondrial e...

Malignant cells have enhanced sensitivity to inhibition of growth by thymidine. Cell growth of the permanent lymphoid cell line CCRF-CEM, originating from a patient with acute lymphoblastic leukemia, is inhibited by 3 x 10(-5) M thymidine, compared to 1 to 5 x 10(-3) M thymidine required to inhibit growth of normal lymphoid lines. Thymidine-resistant cells were isolated at a frequency of approx...

The structural gene for herpes simplex virus (type 1) thymidine kinase was cloned downstream from the X phage high efficiency leftward promotor in a plasmid (pHETK2) also containing the gene for the X cI857 temperature-sensitive repressor. Thymidine kinase is synthesized as a run-on product containing the NH2 terminus of the X N protein. Heat inactivation of the X repressor by growth at 42 O C ...

The expression of thymidine kinase in fungi, which normally lack this enzyme, will greatly aid the study of DNA metabolism and provide useful drug-sensitive phenotypes. The herpes simplex virus type-1 thymidine kinase gene ( tk ) was expressed in Neurospora crassa. tk was expressed as a fusion to N.crassa arg-2 regulatory sequences and as a hygromycin phosphotransferase-thymidine kinase fusion ...