Related Experiment Videos
In vitro selection of self-cleaving DNAs
N Carmi1, L A Shultz, R R Breaker
1Department of Biology, Yale University, New Haven, CT 06520-8103, USA.
Chemistry & Biology
|December 1, 1996
Summary
Researchers have created catalytic DNA molecules, or deoxyribozymes, that can cleave themselves. These DNA enzymes utilize metal ions for catalysis, opening possibilities for DNA-based biocatalysis.
Area of Science:
- Biochemistry
- Molecular Biology
- Catalysis
Background:
- Ribozymes (RNA enzymes) perform crucial metabolic reactions.
- The potential for DNA to act as a catalyst (deoxyribozymes) is largely unexplored.
- The absence of a 2' hydroxyl group in DNA raises questions about its catalytic capabilities.
Purpose of the Study:
- To investigate if DNA can be engineered into catalytic molecules (deoxyribozymes).
- To determine if DNA can exhibit enzyme-like activity despite lacking a 2' hydroxyl group.
- To discover or create DNA biocatalysts.
Main Methods:
- In vitro selection was used to isolate self-cleaving DNA molecules from random sequences.
- Characterization of DNA catalysts involved identifying cofactor requirements (e.g., Cu2+, ascorbate).
- Optimization of catalytic activity through further rounds of in vitro selection.
Main Results:
- Two distinct classes of self-cleaving deoxyribozymes were isolated.
- Class I deoxyribozymes require Cu2+ and ascorbate for oxidative self-cleavage.
- Class II deoxyribozymes use Cu2+ as the sole cofactor, with optimized versions showing over 1,000,000-fold rate enhancement.
Conclusions:
- Single-stranded DNA can form structures enabling metal-dependent oxidative self-cleavage.
- These findings demonstrate the potential for creating efficient DNA enzymes.
- The results suggest DNA biocatalysts could function within biological systems.