Simultaneous improvement of specificity and affinity of aptamers against Streptococcus mutans by in silico maturation for biosensor development.

In silico evolution with an in vitro system can facilitate the development of functional aptamers with high specificity and affinity. Although a general technique known as systematic evolution of ligand by exponential enrichment (SELEX) is an efficient method for aptamer selection, it sometimes fails to identify aptamers with sufficient binding properties. We have previously developed in silico maturation (ISM) to improve functions of aptamers based on genetic algorithms.

Selection of DNA aptamers against insulin and construction of an aptameric enzyme subunit for insulin sensing.

We selected DNA aptamers against insulin and developed an aptameric enzyme subunit (AES) for insulin sensing. The insulin-binding aptamers were identified from a single-strand DNA library which was expected to form various kinds of G-quartet structures. In vitro selection was carried out by means of aptamer blotting, which visualizes the oligonucleotides binding to the target protein at each round.

Selection of DNA aptamers that inhibit enzymatic activity of PQQGDH and its application.

We screened DNA aptamers against the water-soluble quinoprotein glucose dehydrogenase (PQQGDH) with a competitive selection method. PQQGDH is a dimeric enzyme that consists of 50-kDa subunits, and has high catalytic activity for glucose (about 5000 U/mg), therefore is used for glucose sensors in the market. PQQGDH is an excellent molecular recognition device for biosensor for diagnosis.