科研之友
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摘要
The EtNa DNAzyme was isolated during the isopropanol precipitation step of an in vitro selection effort. Although inactive with the intended cofactor, its RNA cleavage activity was observed under a few conditions. With Na+, EtNa was highly active in approximate to 50% ethanol, whereas in water, it was highly active with Ca2+. In this work, we showed that the EtNa DNAzyme was accelerated by freezing in water in the presence of Na+. The apparent K-d value reached 6.2mm Na+ under the frozen condition, over 20 times tighter than that in water at room temperature. With 10mm Na+, EtNa had a cleavage rate of 0.12h(-1) after freezing at -20 degrees C. This effect was unique to EtNa, as all other tested DNAzymes were inhibited by freezing except for the Na+-specific NaA43. Freezing also inhibited EtNa if Ca2+ was used. We attributed this to the concentrations of EtNa and Na+ in the micropockets between ice crystals, but divalent metals might misfold DNA. Overall, we have systematically studied the effect of freezing on the RNA-cleavage activity of DNAzymes. The DNAzyme sequence and the metal ion species are both crucial to determine the effect of freezing.
- 出版日期2018-5-18
- 单位中南大学
