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Studies On Type I And Type Ii Dna Topoisomerases From Mammalian Mitochondria, Jia-Hwei Lin

Theses and Dissertations in Biomedical Sciences

Mammalian mitochondria contain a unique DNA topoisomerase I with characteristics of both nuclear and bacterial type I DNA topoisomerases. This enzyme, purified from bovine liver, requires cations as cofactors and possesses optimal activity at pH 7.0, 37°C and either 150 mM K+ or Na+ ions. Similar to nuclear enzymes and different from the bacterial enzyme, divalent ions such as Ca²⁺ or Mg²⁺ will stimulate but are not essential for the enzymatic activity.

Like the nuclear DNA topoisomerase I, the mitochondrial enzyme is capable of relaxing both negatively and positively supercoiled DNA. The relaxation of negatively supercoiled DNA is …

Analysis Of The Proteoglycan Content In Fresh And Cryopreserved Porcine Cardiovascular Tissues, Yun Hee Shon

Theses and Dissertations in Biomedical Sciences

The purpose of this research was to study the effects of cryopreservation on the proteoglycan (PG) and mineral content of aorta conduit tissue. Proteoglycans from fresh and cryopreserved porcine aorta conduit tissues were isolated by extraction with 4 M guanidine (Gdn) - hydrochloride (HCl) for 48 hours. Quantitative analysis of extracted proteoglycans revealed that the content of proteoglycan material from cryopreserved tissue, measured as uronate and protein per unit weight of wet tissue, was similar to that from fresh tissue. Gel permeation column chromatography studies suggested that proteoglycans present in three CsCl fractions from cryopreserved tissues had molecular weights similar …

Cloning A Putative Dna-Binding Protein Controlling The 5'Ltr Of The Copia Element In Drosophila, Horng-Yuan Kan

Theses and Dissertations in Biomedical Sciences

Copia, a Drosophila retrotransposon, is constitutively expressed in all developmental stages, except the embryo in Drosophila melanogaster. The effect of random integration of the copia element results in phenotypic change in Drosophila. The regulatory sequences, controlling copia expression, are located within the 5'LTR. The DNA sequence in the 5'LTR and in the location between downstream of entire the 5' LTR and the initial translation site have been identified by mobilityshift binding assays and DNase I footprinting assays. The data reveals three protected regions: a TATA-binding site, the AT-1, and AT-2 binding sites. The TATA-binding site and AT-1 site are …