Direct measurements of base stacking interactions in DNA by single-molecule atomic-force spectroscopy.
We investigate the elasticity of two types of single-stranded synthetic DNA homopolydeoxynucletides, poly(dA) and poly(dT), by AFM-based single-molecule force spectroscopy. We find that poly(dT) exhibits the expected entropic elasticity behavior, while poly(dA) unexpectedly displays two overstretching transitions in the force-extension relationship. We suggest that these transitions, which occur at approximately 23 pN and approximately 113 pN, directly capture, for the first time, the mechanical signature of base-stacking interactions among adenines in DNA, in the absence of base pairing.
Ke
Changhong
C
Department of Mechanical Engineering and Materials Science, Center for Biologically Inspired Materials and Material Systems, Duke University, Durham, North Carolina, USA.
Humeniuk
Michael
M
S-Gracz
Hanna
H
Marszalek
Piotr E
PE
D020029:Base Pairing; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force; D011089:Polydeoxyribonucleotides / Q000737:chemistry
D011089:Polydeoxyribonucleotides; D004247:DNA