DNA Hybridization by Peptide Nucleic Acids Attached to Controlled Pore Glass

Abstract

charged backbone of DNA is replaced by a neutral one in PNA, PNA-DNA duplexes are free from electrostatic repulsion between the two negatively charged backbones unlike DNA-DNA duplexes. Consequently, PNA-DNA duplexes have greater stability compared with the corresponding DNADNA duplexes at low salt concentrations. Although formation of PNA-DNA duplexes in solution has been extensively investigated, DNA hybridization by immobilized PNA has been rarely studied. In the present study, we examined whether PNA attached to controlled pore glass (CPG) can form strong and specific complex with DNA dissolved in solution. CPG is silica glass with uniform and controlled pores. A glycerol-containing CPG derivative (CPG-glycerol) was oxidized with NaIO4 to obtain an aldehyde-containing CPG derivative (CPG-CHO) in the present study. Then, the terminal amino group of a PNA molecule was linked to CPG-CHO by reductive amination with sodium cyanoborohydride. In Table 1, PNAs attached to CPG are summarized, together with DNAs used as substrates. HoPuPNA, HoPyPNA, and MSPNA are complementary to HoPyDNA, HoPuDNA, and MSDNA, respectively. When HoPyDNA, HoPuDNA, and MSDNA were incubated with the PNA-free CPG-glycerol under the conditions of hybridization conditions, the amount of the DNA adsorbed onto the resin was negligible. This suggests that adsorption of DNA onto the PNA-containing CPG (CPG-PNA) would