Study On Comparison Between The Methods Of Screening Aptamers Of Ricin Toxin

Ricin toxin is derived from castor beans and composed of two glycoproteins chains A and chains B linked by a disulfide bond. The enzymatically active A chain can inactivate ribosome rRNA and therefore stop protein synthesis. The B chain has twogalactose-binding sites.SELEX (Systematic Evolution of Ligands by Exponential Enrichment), also known as in vitro selection, is a technique for screening large nucleic acid libraries to obtain oligonucleotide aptamers that bind targets with high affinity and specificity. As aptamers can bind a wide variety of targets, including small molecules, peptides, proteins and cells, with high affinity and specificity, SELEX technique has promising applications in basic research, drug screening, and clinical diagnosis et.al. The objective of this research is to screen aptamers against ricin toxin proteins from a random ssDNA library by SELEX technique, in order to provide basic data for using aptamers as biosensors recognition elements and prophylactic or therapeutic agents of ricin. We designed and synthesized an 87 nucleotides ssDNA pool containing 40 random nucleotides flanked by invariant binding regions for PCR primers. First, we screened out specific aptamers for ricin by conventional SELEX, which used microtiter...