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OverviewThe polyamines spermine and spermidine play important roles in many cellular processes, and unusual levels of these polyamines have been associated with numerous human diseases. Spermidine/spermine N1-acetyltransferase (SSAT) is an enzyme involved in polyamine regulation, where acetylation of polyamines by SSAT ultimately leads to their degradation or export from the cell. In this dissertation, x-ray crystallography and nuclear magnetic resonance (NMR) are used to provide insights into the structure and function of this important enzyme. X-ray crystallography provided two distinct views of SSAT: one of the enzyme in complex with coenzyme A (CoA), and another of the enzyme in complex with CoA and the polyamine spermine. Together, the two structures reveal structural plasticity in the active site of the enzyme. The complex with spermine provides a direct view of polyamine binding by SSAT, and shows that the enzyme relies heavily on associated water molecules to bind spermine; these water molecules also appear to form a proton relay between the primary amine of spermine and the side-chain of a conserved glutamate residue. Guided by the structural results, NMR methods were used to test hypotheses regarding the enzyme mechanism of SSAT. The activity of the enzyme over a range of solution conditions, and towards different polyamine substrates, was determined; the effects of mutating single amino acids in the enzyme were also evaluated. The enzyme appeared to be most active between pH 8.5 and 9.5, and mutation of the aforementioned glutamate significantly altered this behavior. This suggests the glutamate is directly involved in the acetyltransfer reaction, where it likely functions as a catalytic base though the proton relay in the enzyme active site. These studies advance our general understanding of how polyamines are regulated in mammalian cells, and have the potential to assist in developing new therapeutic options for human diseases involving polyamines. Full Product DetailsAuthor: Eric John MontemayorPublisher: Proquest, Umi Dissertation Publishing Imprint: Proquest, Umi Dissertation Publishing Dimensions: Width: 20.30cm , Height: 0.90cm , Length: 25.40cm Weight: 0.286kg ISBN: 9781243985958ISBN 10: 124398595 Pages: 136 Publication Date: 01 September 2011 Audience: General/trade , General Format: Paperback Publisher's Status: Active Availability: Temporarily unavailable The supplier advises that this item is temporarily unavailable. It will be ordered for you and placed on backorder. Once it does come back in stock, we will ship it out to you. Table of ContentsReviewsAuthor InformationTab Content 6Author Website:Countries AvailableAll regions |