Cristofalo, Matteo; Kovari, Daniel; Corti, Roberta; Salerno, Domenico; Cassina, Valeria; Dunlap, David; Mantegazza, Francesco published the artcile< Nanomechanics of Diaminopurine-Substituted DNA>, Related Products of 452-06-2, the main research area is diaminopurine double strand DNA nanomechanics.
2,6-Diaminopurine (DAP) is a nucleobase analog of adenine. When incorporated into double-stranded DNA (dsDNA), it forms three hydrogen bonds with thymine. Rare in nature, DAP substitution alters the phys. characteristics of a DNA mol. without sacrificing sequence specificity. Here, we show that in addition to stabilizing double-strand hybridization, DAP substitution also changes the mech. and conformational properties of dsDNA. Thermal melting experiments reveal that DAP substitution raises melting temperatures without diminishing sequence-dependent effects. Using a combination of at. force microscopy (AFM), magnetic tweezer (MT) nanomech. assays, and CD spectroscopy, we demonstrate that DAP substitution increases the flexural rigidity of dsDNA yet also facilitates conformational shifts, which manifest as changes in mol. length. DAP substitution increases both the static and dynamic persistence length of DNA (measured by AFM and MT, resp.). In the static case (AFM), in which tension is not applied to the mol., the contour length of DAP-DNA appears shorter than wild-type (WT)-DNA; under tension (MT), they have similar dynamic contour lengths. At tensions above 60 pN, WT-DNA undergoes characteristic overstretching because of strand separation (tension-induced melting) and spontaneous adoption of a conformation termed S-DNA. Cyclic overstretching and relaxation of WT-DNA at near-zero loading rates typically yields hysteresis, indicative of tension-induced melting; conversely, cyclic stretching of DAP-DNA showed little or no hysteresis, consistent with the adoption of the S-form, similar to what has been reported for GC-rich sequences. However, DAP-DNA overstretching is distinct from GC-rich overstretching in that it happens at a significantly lower tension. In physiol. salt conditions, evenly mixed AT/GC DNA typically overstretches around 60 pN. GC-rich sequences overstretch at similar if not slightly higher tensions. Here, we show that DAP-DNA overstretches at 52 pN. In summary, DAP substitution decreases the overall stability of the B-form double helix, biasing toward non-B-form DNA helix conformations at zero tension and facilitating the B-to-S transition at high tension.
Biophysical Journal published new progress about Conformational transition. 452-06-2 belongs to class imidazoles-derivatives, and the molecular formula is C5H5N5, Related Products of 452-06-2.
Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem