Abstract:
:Herpes simplex virus type 1 (HSV-1) thymidine kinase is currently used as a suicide agent in the gene therapy of cancer. This therapy is based on the preferential phosphorylation of nucleoside analogs by tumor cells expressing HSV-1 thymidine kinase. However, the use of HSV-1 thymidine kinase is limited in part by the toxicity of the nucleoside analogs. We have used random sequence mutagenesis to create new HSV-1 thymidine kinases that, compared with wild-type thymidine kinase, render cells much more sensitive to specific nucleoside analogs. A segment of the HSV-1 thymidine kinase gene at the putative nucleoside binding site was substituted with random nucleotide sequences. Mutant enzymes that demonstrate preferential phosphorylation of the nucleoside analogs, ganciclovir or acyclovir, were selected from more than one million Escherichia coli transformants. Among the 426 active mutants we have isolated, 26 demonstrated enhanced sensitivity to ganciclovir, and 54 were more sensitive to acyclovir. Only 6 mutant enzymes displayed sensitivity to both ganciclovir and acyclovir when expressed in E. coli. Analysis of 3 drug-sensitive enzymes demonstrated that 1 produced stable mammalian cell transfectants that are 43-fold more sensitive to ganciclovir and 20-fold more sensitive to acyclovir.
journal_name
Proc Natl Acad Sci U S Aauthors
Black ME,Newcomb TG,Wilson HM,Loeb LAdoi
10.1073/pnas.93.8.3525subject
Has Abstractpub_date
1996-04-16 00:00:00pages
3525-9issue
8eissn
0027-8424issn
1091-6490journal_volume
93pub_type
杂志文章abstract::One of the most basic predictions of almost any model of crime is that individual time preferences matter. However, empirical evidence on this fundamental property is essentially nonexistent. To our knowledge, this paper provides the first pieces of evidence on the link between time discounting and crime. We use a uni...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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