The methodology for selecting DNA aptamer to MPT164 protein from Mycobacterium tuberculosis with SELEX technology / 中华微生物学和免疫学杂志

ABSTRACT

Objective To obtain DNA oligonucleotide aptamers which can specifically bind to MPT64 protein from Mycobacterium tuberculosis by SELEX(systematic evolution of ligands by exponential enrichment)technology. Methods A random ssDNA library with in vitro synthesized 78 nucleotides in length was subiected to 12 rounds of selection by SELEX method against MPT64 protein. The binding ability of the aptamers to the protein was examined by biotin-streptavidin-horseradish peroxidase system. Results The selective system used was as followsin PCR amplification,annealing temperature was 65℃ and the concentration of Mg2+ was 1.5 mmol/L in optimizing library, and when preparation of ssDNA with asymmetrical PCR amplification, 0.75 mmol/L of Mg2+ was used. When using the plate for ELISA as the substrate for the selection, the pattern of electrophoretic band of PCR product after the tenth round selection became unitary and denser than that of the first round. The binding assay demonstrated that A value at 450 nm of the tenth round increased by 9.18 times as compared with that of the first round. The results showed that the affinities of the aptamers were different. The highest A value at 450 nm was 1.606, and the lowest 0.572. Conclusion A set of aptamers with considerable binding affinity to MPT64 protein are successfully picked out from the initial random DNA library.