In vitro selection methods

This biopanning procedure, which represents the most frequently used in vitro selection method [48-59], is represented schematically in Figure 19.1. 

The adaptability of in vitro selection to a panel of ligands34,35 is applicable to the RNP-based selection scheme. RNP receptors for GTP were isolated from the pool of RNP library by the in vitro selection method described for the selection of ATP-binding RNP.39 The sequences of the RNA subunit of GTP-binding RNPs revealed that there... 

Tang, J., Xie, J., Shao, N. and Yan, Y. (2006) The DNA aptamers that specifically recognize ricin toxin are selected by two in vitro selection methods. Electrophoresis, 27, 1303-1311. 

In vitro selection methods permit the generation of ribozymes and deoxyribozymes (catalytic DNA) with allosteric properties, wherein the binding of an effector molecule controls the catalytic function. This feature provides challenging opportunities for the development of new analytical and very specific tools using traditional assay formats or for the development of entirely new biosensing principles. 

As mentioned above, once freed from the constraints of a complementary strand, polynucleotides can fold into a wide range of three-dimensional structures, leading to a diverse array of functions. Two specific types of functional polynucleotides are (1) aptamers, which bind noncovalently but selectively to ligands and (2) enzymes, which catalyze chemical reactions similar to protein enzymes. While a few examples of both natural aptamers and enzymes have been discovered, far more have been identified from synthetic combinatorial libraries through in vitro selection methods. The general approach to selection of functional polynucleotides is described below, followed by specific examples of nucleic acid-based aptamers and enzymes. 

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