Viscosity study of DNA. II. The effect of simple salt concentration on the viscosity of high molecular weight DNA and application of viscometry to the study of DNA isolated from T4 and T5 bacteriophage mutants
✍ Scribed by Philip D. Ross; Robert L. Scruggs
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1968
- Tongue
- English
- Weight
- 707 KB
- Volume
- 6
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Polyelectrolyte expansion effects on high molecular weight bacteriophage DNA have bcen studied by examining the influence of simple salt concentration upon the intrinsic viscosity, [TI. The viscosity-molecular weight exponent a in the expression [q] = KM. diminishes from 0.8 in 0.005M simple salt to a limiting value of 0.6 for salt concentrations greater than 0.6M at 25°C. The B parameter of the Nl+'hydrodynamic representation thus varies from approximately 0.2-0.07 over this range of salt concentration. The iutrinsic viscosity of DNA decreases slightly with increasing temperature at low and moderate salt concentratioiis but becomes independent of temperature at high salt concentrations. The expansion of the DNA molecular domain is linear in the reciprocal square root of the simple salt concentration. Viscosity differences among DNA's isolated from several bacteriophage T5 mutants reflect small differences in molecular wcight which are in agreement with size determination by other techniques. The DNA's isolated from various rII mutants of T4 bacteriophage including some very large deletion mutations were found to be identically the same size in accord with currcnt genetic ideas. Details of the representation and extrapolation of viscosity data are discussed and thc sensitivity of the technique is evaluated.