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Type of Document	Dissertation
Author	Hearst, John E.
URN	etd-04072006-090550
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-04072006-090550
Title	Ultracentrifuge studies on deoxyribonucleic acid and tobacco mosaic virus. I. The effect of angular velocity on the sedimentation velocity behavior of DNA and TMV. II. The three component theory of sedimentation equilibrium in a density gradient and the hydration of DNA. III. The effects of pressure on the buoyant behavior of DNA and TMV in a density gradient at equilibrium
Degree	PhD
Option	Chemistry
Advisory Committee	Advisor Name Title Jerome Rubin Vinograd Committee Chair
Keywords	none
Date of Defense	1961-01-01
Availability	unrestricted
Abstract Part 1 - A dependence of sedimentation coefficient and sedimentation boundary shape upon the angular velocity of the ultracentrifuge has been observed for T-4 bacteriophage deoxyribonucleic acid (DNA), E. coli DNA, and tobacco mosaic virus. The effects resulting from extrapolation of high-speed data are discussed along with possible causes of the phenomenon. Part 2 - T-4 bacteriophage DNA is renatured by slow dialysis of a sodium citrate buffer solution into a solution of DNA in formamide. The first step in the renaturation appears to require the formation of approximately fifty percent of the possible hydrogen bonds. Part 3 - The dependence of the buoyant density of DNA on the presence of a second cation is studied and a theory presented. The system enables one to evaluate a relative binding constant of the two cations to DNA. Part 4 - The theory of density gradient sedimentation equilibrium including the effects of solvation is presented. The correction terms necessary for the evaluation of an anhydrous molecular weight are shown to be experimentally available. DNA is observed to have a large hydration parameter which is strongly dependent on water activity. Part 5 - The theory for the effect of pressure on the density gradient in a concentrated salt solution is presented. The effect of pressure on the buoyant density of DNA and tobacco mosaic virus is measured and found to be a linear function of pressure. Part 6 - The apparent molecular weight of T-4 bacteriophage DNA is evaluated using the density gradient sedimentation equilibrium theory presented in Parts 4 and 5. The DNA appears to have density heterogeneity.
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