title: [Effect of 3' exonuclease activity of polymerase on extension of phosphorothioate-modified primers].
abstract: OBJECTIVE
  To determine whether 3'phosphorothioate-modified-2 terminal mismatched primers can turn off DNA polymerization mediated by Exo(+) polymerase.
  
  
  METHODS
  Two-directional primer extension was performed using polymerase with and without 3' exonuclease activity. The effects of unmodified primers and 3' phosphorothioate-modified primers on primer extension were evaluated.
  
  
  RESULTS
  Exo(-) polymerase yielded products from matched and mismatched primers regardless of their modification. However, 3' phosphorothioate-modified primers with a single base mismatch at -2 position worked similarly to the terminal (-1) mismatched primers in triggering the novelly reported "off-switch" of Exo(+) polymerase.
  
  
  CONCLUSIONS
  These data suggested that the "off-switch" can be of enormous application in the diagnosis of single gene diseases and in the association studies by single nucleotide polymorphism screening.
authors.affiliation: Department of Pharmacy and Pharmacology, Nanhua University, Hengyang, Hunan, 421001 PR China.
authors.forename: Zi-fen
authors.initials: ZF
authors.lastname: Guo
authors.forename: Lin-ling
authors.initials: LL
authors.lastname: Chen
authors.forename: Jia
authors.initials: J
authors.lastname: Zhang
authors.forename: Cui-ying
authors.initials: CY
authors.lastname: Peng
authors.forename: Xiang-dong
authors.initials: XD
authors.lastname: Yang
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Shu-ya
authors.initials: SY
authors.lastname: He
authors.forename: Duan-fang
authors.initials: DF
authors.lastname: Liao
authors.forename: Kai
authors.initials: K
authors.lastname: Li
mesh_terms: D017931:DNA Primers / Q000737:chemistry / Q000235:genetics*; D005092:Exonucleases / Q000378:metabolism*; D006801:Humans; D054735:Phosphorothioate Oligonucleotides / Q000737:chemistry / Q000235:genetics*; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide
chemical_list: D017931:DNA Primers; D054735:Phosphorothioate Oligonucleotides; D005092:Exonucleases