## Abstract The strand‐separation transition of T7 DNA has been investigated by temperature shift and viscosity measurements in two formamide–water solvents. The strand‐separation region is quite narrow, and follows directly at the end of the denaturation transition observed by absorbance. The kine
Intermediates in the strand-separation transition of T7 DNA
✍ Scribed by C. Glen Wensley; M. Thomas Record Jr.
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1976
- Tongue
- English
- Weight
- 623 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
Sedimentation velocity runs as a function of temperature in the region of the alkaline helix‐coil transition have enabled us to demonstrate the existence of stable two‐stranded intermediates in the strand‐separation process for T7 DNA. The strand‐separation transition under these conditions has an intrinsic breadth of ∼1°C, and within this temperature range (T~m~ + 2°C < T < T~m~ + 3°C) the intermediate forms are progressively converted (as a function of temperature) to single‐stranded DNA. Parallel characterizations of the strand‐separation transition by viscosity and absorbance–renaturation studies in the alkaline solvent are entirely consistent with the sedimentation experiments. Comparison of the experimental mean sedimentation coefficient of the intermediate forms with theoretical predictions for branched structures suggests that in these molecules the two strands are connected at a single point, not centrally located with respect to the ends of the molecule.
📜 SIMILAR VOLUMES
The structure of the packaged double-stranded DNA genome of bacteriophage T7 was compared to that of unpackaged T7 DNA using digital difference Raman spectroscopy. Spectral data were obtained at 25 degrees C from native T7 virus (100 mg/mL), empty T7 capsids (50 mg/mL), and purified T7 DNA (40 mg/mL
The time required for the completion of the process of strand separation ill X bacteriophage DNA preparations exposed to strongly alkaline conditions in aqueous glycerol solutions was directly proportional to the viscosity of the solvent. This finding s u p ports the idea that the rate-limiting step