THE CHARACTERIZATION OF A NEW SINGLE STRAND DNA BINDING PROTEIN (SSB-B) ISOLATED FROM AN ESCHERICHIA COLI SSB(-) MUTANT.
Item
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Title
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THE CHARACTERIZATION OF A NEW SINGLE STRAND DNA BINDING PROTEIN (SSB-B) ISOLATED FROM AN ESCHERICHIA COLI SSB(-) MUTANT.
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Identifier
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AAI8203310
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identifier
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8203310
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Creator
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OSHMAN, ROBIN GAIL.
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Contributor
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James G. Wetmur
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Date
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1981
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Microbiology
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Abstract
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A protein (SSB-B) has been isolated from an Escherichia coli (E. coli) temperature sensitive single strand DNA binding protein mutant (ssb('-)) which is not isolated from the wild type strain using the same procedures. SSB-B has a molecular weight of 17,800 daltons as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The temperature sensitive and wild type E. coli single strand DNA binding proteins (SSB) have a molecular weight of approximately 18,500 daltons as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. SSB-B differs qualitatively from temperature sensitive and wild type E. coli SSB in its antigenic determinants as determined by an enzyme linked immunosorbent assay. SSB-B differs quantitatively from E. coli wild type SSB in its ability to protect single stranded DNA in a DNase I-snake venom phosphodiesterase nuclease protection assay. SSB-B differs from wild type SSB in the nature of its binding to single stranded DNA. An SSB-B-single strand DNA complex is extremely hydrophobic and binds to most surfaces. A wild type SSB-single strand DNA complex remains in solution. The amino acid composition of SSB-B is unlike any other E. coli DNA binding protein amino acid composition published to date. None of the E. coli proteins capable of binding to single strand DNA have a molecular weight identical to SSB-B. After studying the sequence of wild type E. coli SSB, it was determined that SSB-B could not be a processed product of SSB, but must be a unique protein. Using an equilibrium dialysis assay, SSB-B was shown to have a noncooperative binding constant identical to that of wild type SSB. Electron micrographs of SSB-B-single strand DNA complexes show that under certain conditions the protein appears to bind cooperatively to single strand DNA. These complexes are more extended than wild type SSB-single strand DNA complexes. SSB-B is therefore believed to be a single strand DNA binding protein never before isolated from E. coli.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
