Biographical Memoirs Volume 89 (2007) / Chapter Skim
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JEROME VINOGRAD
JEROME VINOGRAD
Pages 356-367
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From page 356... ...
Courtesy of the Archives, California Institute of Technology
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From page 357... ...
During 1941-1951, Vinograd worked for the Shell Development Company on the use of emulsion polymerization to produce synthetic rubber and on problems of catalysis to manufacture aviation gasoline. In 1951 he moved to the Department of Chemistry at the California Institute of Technology, first as a senior research fellow, then in 1956 as a research associate, and in 1966 as a professor of chemistry and biology.
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From page 358... ...
DENSITY GRADIENT ULTRACENTRIFUGATION Vinograd's initial major contribution was the development of density gradient ultracentrifugation. This was stimulated by Matthew Meselson and Frank Stahl, who were seeking a means to implement their bold experiment to verify the hypothesis that DNA replication involved the separation of the two parental strands, one going into each of the two daughter DNA molecules.
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From page 359... ...
Several later papers refined the theory and extended the density gradient technique in its application to macromolecules. A variation that employed a lamella of the macromolecules layered on a self-generating density gradient permitted more rapid determination of their sedimentation and diffusion coefficients.
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From page 360... ...
As the maximum amount of dye that can be bound by the closed circular molecule is less than can be bound by the linear or nicked circular molecule and as the buoyant density of the DNA-dye complex is inversely related to the amount of dye bound, the buoyant density of the closed circular DNA-dye complex is greater than that of the linear DNA or nicked circular DNA-dye complexes. At saturating amounts of ethidium bromide the buoyant density difference is approximately 0.04 gm/ml in CsCl.
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From page 361... ...
Alternatively, at high dye concentration the buoyant density difference between open and closed forms of SV40 DNA was shown to be approximately constant because of the free energy required to form positive superhelixes. This buoyant energy difference is quantitatively related to the native superhelix density.
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From page 362... ...
MITOCHONDRIAL DNA Further studies of mitochondrial DNA from varied sources found the common presence of circular oligomers and of catenated oligomers. In a CsCl-ethidium bromide density gradient the closed oligomer bands at the same density as the monomer, although its sedimentation velocity is significantly greater.
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From page 363... ...
Later replication of the "light" strand commences at about 60 percent from the "origin," proceeding counterclockwise. The discovery that closed circular mitochondrial DNAs of about 10 million molecular weight invariably suffered chain scissions at high pH led to the suggestion of covalently incorporated ribonucleotides.
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From page 364... ...
Professor Vinograd died suddenly at the age of 63. FOR THEIR ASSISTANCE , I am indebted to the staff of the archives of the California Institute of Technology.
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From page 365... ...
The evaluation of standard sedimentation coeffi cients of sodium RNA and sodium DNA from sedimentation ve locity data in concentrated NaCl and CsCl solutions. Biochim.
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From page 366... ...
In vivo effects of intercalating drug on the superhelix density of mitochondrial DNA isolated from human and mouse cells in culture.
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