โ Scribed by Luis A. Marky; Kenneth J. Breslauer
No coin nor oath required. For personal study only.
Differential scanning calorimetry was used to directly determine the transition enthalpies accompanying the duplexโtoโsingleโstrand transition of poly[d(AT)], poly(dA)ยทpoly(dT), poly[d(AC)]ยทpoly[d(TG)], and d(GCGCGC). The calorimetric data allow us to define the following average baseโstacking enthalpies:
| Interaction | ฮ__H__ (kcal/stack) |
|---|---|
| AC/TG, TG/AC | 5.6 |
| AT/TA, TA/AT | 7.1 |
| AA/TT | 8.6 |
| GC/CG, CG/GC | 11.9 |
Comparison with published data on the corresponding RNA interactions reveals remarkably good agreement. By assuming transition enthalpies to result from the pairwise disruption of nearestโneighbor stacking interactions, we used the enthalpy data listed above to predict the transition enthalpies for three oligomeric DNA duplexes. Excellent agreement was found between the predicted and the calorimetrically determined values.
๐ SIMILAR VOLUMES
## Abstract Aromatic stacking and hydrogen bonding between nucleobases are two of the key interactions responsible for stabilization of DNA doubleโhelical structures. The present work aims at defining the specific contributions of these interactions to the stability of individual base pairs in DNA.