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Attempt to Crystallize Human Asparagine Synthetase Bound to Two Inhibitors
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 Material Information
Title: Attempt to Crystallize Human Asparagine Synthetase Bound to Two Inhibitors
Series Title: Journal of Undergraduate Research
Physical Description: Serial
Language: English
Creator: Berry, Alexandria H.
Li, Kai
Kursula, Inari
Lindqvist, Ylva
Richards, Nigel G. J. ( Mentor )
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009
Abstract: Drug resistance in acute lymphoblasitic leukemia (ALL) is an ongoing problem. Resistance to asparaginase (ASNase) treatment – a treatment believed to work by breaking down asparagine in the blood and therefore starving leukemia cells – is linked to up-regulation of human asparagine synthetase (hASNS), the enzyme that produces asparagine. The purpose of this work was to obtain a crystal structure of hASNS with inhibitors bound to both of its active sites. A structure would be used to design potent inhibitors of hASNS to treat ASNase resistance. Conditions for inhibition of the glutaminase active site by 6-diazo-5-oxo-L-norluecine and the synthetase site by a transition state analog, a sulfoximine, were determined. The Ki and and Ki* describing sulfoximine inhibition of DON-inhibited hASNS were found to be 679 nM and 2.9 nM, respectively. The DON-inhibited enzyme was more difficult to inhibit with the sulfoximine than the free enzyme. Milligram amounts of the doubly-inhibited enzyme were screened for crystallization conditions using the sitting drop method. Crystals were obtained, but no structure could be determined. The inhibition studies suggest a possible conformational change in the synthetase site upon the binding of glutamine to the glutaminase site. The crystallization screens revealed increased hASNS solubility at pH 9. From this information, we hope that a crystal structure of hASNS will soon be realized.
 Record Information
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UF00091523:00571

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