Example sentences for: abasic

How can you use “abasic” in a sentence? Here are some example sentences to help you improve your vocabulary:

  • The endonuclease activity of DNase 1 is reduced many fold by integrating this loop from E. coli exonuclease III, but the mutant cleaves at abasic sites in DNA with low efficiency [ 29 ] . Thus additional residues in the APEs control specificity while still allowing a reasonable rate of phosphorolytic cleavage.

  • An alanine substitution mutant, N226A, of a conserved residue at the end of molego 7a that forms a hydrogen bond with the second phosphate group downstream of the abasic site, had enhanced APE activity but increased Km and Kd values, similar to an alanine mutant of R177, which binds to the same site, reported previously [ 34 ] . A combination of the two mutants, N226A and R177A, substantially reduced the ability of APE1 to bind to DNA containing an abasic site (Izumi et al.

  • The abasic sugar-phosphate backbone is then cleaved by an apurinic/apyrimidinic endonuclease or lyase.

  • This generates the necessary 3' hydroxyl group for DNA polymerases (pol β, δ or ε, in eukaryotes) to insert the correct nucleotide in later steps in the base excision repair pathway (BER-pathway) [ 7 8 ] . Recent crystal structures of huAPE1 complexed with DNA containing an abasic site [ 9 10 11 ] , combined with sequence analysis and site-directed mutagenesis, have defined the residues that participate in metal ion based cleavage of the phosphate backbone of the DNA [ 12 13 14 15 16 17 ] .

  • For example, Herschlag and co-workers have previously shown that a nucleobase could complement an abasic site within the hammerhead ribozyme, restoring cleavage activity [ 1 ] . Similarly, Porta and Lizardi engineered a hammerhead ribozyme that assumed an inactive secondary structure; upon the addition of an oligonucleotide that disrupted the engineered secondary structure, the ribozyme was activated [ 2 ] . More recently, it has previously been shown that many selected nucleic acid binding species (aptamers) undergo conformational changes upon ligand binding [ 3 4 5 6 ] In addition, when aptamers are conjoined to ribozymes, the ligand-induced conformational changes in the aptamers frequently modulate the structures and hence the activities of the ribozymes [ 7 8 9 ] For example, binding of theophylline to the anti-theophylline aptamer [ 10 ] modulates the conformation of residue [ 11 12 ] and the overall stability of the aptamer [ 10 13 ] . Appending the anti-theophylline aptamer to the hammerhead ribozyme allowed cleavage activity to be modulated by 110-fold by theophylline [ 13 ] . Similarly, appending the anti-theophylline aptamer to a small ribozyme ligase (L1) generated an aptazyme that was activated 1,600-fold by saturating theophylline concentrations [ 14 ] .

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