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Biochemistry, Biophysics, and Structural Biology Commons™

Open Access. Powered by Scholars. Published by Universities.®

Clemson University

2008

Articles 1 - 3 of 3

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Novel Xanthine And Oxanine Dna Glycosylase Activities In Yeast And Mammalian Systems, Liang Dong Dec 2008

Novel Xanthine And Oxanine Dna Glycosylase Activities In Yeast And Mammalian Systems, Liang Dong

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DNA that stores genetic information is frequently damaged in cells. The DNA bases carrying an exocyclic amino group [adenine (A), guanine (G), cytosine (C)] encounter deamination even under physiological conditions. Xanthine (X) and the newly discovered oxanine (O) are derived from deamination of guanine; they are potentially cytotoxic and mutagenic lesions. However, in yeast and eukaryotes, studies on the enzymatic repair of these lesions are limited.
In the yeast, Schizosaccharomyces pombe thymine-DNA glycosylase (Spo TDG) is homologous to human thymine-DNA glycosylase (hTDG), an enzyme that removes thymine from T/G pair. It was reported that Spo TDG contains uracil DNA glycosylase …

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Dna Deamination Repair Enzymes In Bacterial And Human Systems, Rongjuan Mi Dec 2008

Dna Deamination Repair Enzymes In Bacterial And Human Systems, Rongjuan Mi

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DNA repair enzymes and pathways are diverse and critical for living cells to maintain correct genetic information. Single-strand-selective monofunctional uracil DNA glycosylase (SMUG1) belongs to Family 3 of the uracil DNA glycosylase superfamily. We report that a bacterial SMUG1 ortholog in Geobacter metallireducens (Gme) and the human SMUG1 enzyme are not only uracil DNA glycosylases (UDG), but also xanthine DNA glycosylases (XDG). Mutations at M57 (M57L) and H210 (H210G, H210M, H210N) can cause substantial reductions in XDG and UDG activities. Increased selectivity is achieved in the A214R mutant of Gme SMUG1 and G60Y completely abolishes XDG and UDG activity. Most …

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Dendrimer Supramolecular Assembly For Gene Delivery, Karthikeyan Pasupathy Jul 2008

Dendrimer Supramolecular Assembly For Gene Delivery, Karthikeyan Pasupathy

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Dendrimers have found many applications in the fields of polymer science, biophysics, nanomedicine and the petroleum industry. Poly(amidoamine) (PAMAM) was studied as a model dendrimer and squalane as a model hydrocarbon. The interaction between PAMAM and squalane is pH dependent. Specifically, at low or neutral pH the squalane is found on the periphery of the PAMAM while at high pH the hydrocarbon is entrapped inside the PAMAM molecules.

Single-molecule fluorescence revealed that the interaction between PAMAM and squalane is reversible. At a pH value of 8, the time constants for the approaching, binding and dissociation of single PAMAM to squalane …

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