Screening and structure analysis of the aptamers against human recombinant S100A8 protein

To obtain and characterize the single-stranded DNA (ssDNA) aptamers of human recombinant S100A8 protein.According to systematic evolution of ligands by exponential enrichment (SELEX) method, an ssDNA random library was subjected to 11 rounds of selection against human recombinant S100A8 protein. Using a biotin-strepavidin-HRP detecting system, the binding capacity of ssDNA to targeted protein from each round was monitored, until the binding level reached a saturation state. Then the ssDNA from the last cycle were cloned and sequenced, and the sequences were further analyzed by programs of bioinformatics.After 11 cycles of selection, 30 clones were selected randomly and sent to sequence analysis. A unique conserved sequence was not obtained among the 30 aptamers by the primary structure analysis, but three aptamers were found identical with three other aptamers respectively. The secondary structure analysis revealed that stem-loop and pocket were the main motifs, indicating that they may play a key role in the binding of aptamers to human recombinant S100A8 protein. According to the ratio of stem-loop to pocket, 30 aptamers were divided into 4 groups, and the affinity of aptamer No. 35 from group I was the highest.Aptamers against human recombinant S100A8 protein were identified by SELEX method, which laid the basis for the further application of the aptamers and the function study of human recombinant S100A8 protein.PubMed0111-64