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A modified polymerase chain reaction (PCR) was developed to introduce random point mutations into cloned genes. The modifications were made to decrease the fidelity of Taq polymerase during DNA synthesis without significantly decreasing the level of amplification achieved in the PCR. The resulting PCR products can be cloned to produce random mutant(More)
An in vitro selection procedure was used to develop a DNA enzyme that can be made to cleave almost any targeted RNA substrate under simulated physiological conditions. The enzyme is comprised of a catalytic domain of 15 deoxynucleotides, flanked by two substrate-recognition domains of seven to eight deoxynucleotides each. The RNA substrate is bound through(More)
All life that is known to exist on Earth today and all life for which there is evidence in the geological record seems to be of the same form--one based on DNA genomes and protein enzymes. Yet there are strong reasons to conclude that DNA- and protein-based life was preceded by a simpler life form based primarily on RNA. This earlier era is referred to as(More)
Theories of the origin of optical asymmetry in living systems place fundamental importance on the amplification of optical asymmetry by an autocatalytic process. The replication of a polynucleotide is one obvious choice for such an autocatalytic growth mechanism. If an optically homogeneous polynucleotide could replicate by directing the polymerization of(More)
BACKGROUND Several types of RNA enzymes (ribozymes) have been identified in biological systems and generated in the laboratory. Considering the variety of known RNA enzymes and the similarity of DNA and RNA, it is reasonable to imagine that DNA might be able to function as an enzyme as well. No such DNA enzyme has been found in nature, however. We set out(More)
Just as Darwinian evolution in nature has led to the development of many sophisticated enzymes, Darwinian evolution in vitro has proven to be a powerful approach for obtaining similar results in the laboratory. This review focuses on the development of nucleic acid enzymes starting from a population of random-sequence RNA or DNA molecules. In order to(More)
Molecular self-assembly offers a means of spontaneously forming complex and well-defined structures from simple components. The specific bonding between DNA base pairs has been used in this way to create DNA-based nanostructures and to direct the assembly of material on the subnanometre to micrometre scale. In principle, large-scale clonal production of(More)