Triplex catalysis

Triplex catalysis.1 1,3-Cyclohexadiene does not undergo cycloadditions under usual conditions although it is known to dimerize on irradiation in the presence of a sensitizer. Actually, 1,3-cyclohexadiene can undergo both [2 + 2]- and [4 + 2]cycloaddition with a silyl enol ether such as 1-trimethylsiloxy-l-phenylethyl-ene (1). Similar results obtain with trimethylsilylketene acetal. These sensitized... 

In addition to the major double-helical form, DNA also exists as triplexes and quadruplexes and forms complex three-way or four-way junctions. Single-stranded DNA has been shown in vitro to fold into complex, stable three-dimensional folds and to bind to smah molecules (such DNA molecules are named aptamers) or to catalyze reactions in a way similar to proteins (so-caUed deoxyribozymes or DNAzymes) [4]. This increased structural diversity makes it a more attractive host molecule for hybrid catalysis [5]. Furthermore, directed evolution approaches are easier to conduct with nucleic acids than with proteins, as nucleic acids can be directly rephcated and amphfied. 

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