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'''Crystal structure of human arginase I: the mutant E256Q''' | '''Crystal structure of human arginase I: the mutant E256Q''' | ||
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[[Category: Guadalupe, S.]] | [[Category: Guadalupe, S.]] | ||
[[Category: Mora, A.]] | [[Category: Mora, A.]] | ||
[[Category: | [[Category: Hydrolase]] | ||
[[Category: | [[Category: Mutant e256q]] | ||
[[Category: | [[Category: Twinned crystal]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 14:11:11 2008'' | |||
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Revision as of 11:11, 3 May 2008
Crystal structure of human arginase I: the mutant E256Q
Overview
The structure of the trimeric, manganese metalloenzyme, rat liver arginase, has been previously determined at 2.1-A resolution (Kanyo, Z. F., Scolnick, L. R., Ash, D. E., and Christianson, D. W., (1996) Nature 383, 554-557). A key feature of this structure is a novel S-shaped oligomerization motif at the carboxyl terminus of the protein that mediates approximately 54% of the intermonomer contacts. Arg-308, located within this oligomerization motif, nucleates a series of intramonomer and intermonomer salt links. In contrast to the trimeric wild-type enzyme, the R308A, R308E, and R308K variants of arginase exist as monomeric species, as determined by gel filtration and analytical ultracentrifugation, indicating that mutation of Arg-308 shifts the equilibrium for trimer dissociation by at least a factor of 10(5). These monomeric arginase variants are catalytically active, with k(cat)/K(m) values that are 13-17% of the value for wild-type enzyme. The arginase variants are characterized by decreased temperature stability relative to the wild-type enzyme. Differential scanning calorimetry shows that the midpoint temperature for unfolding of the Arg-308 variants is in the range of 63.6-65.5 degrees C, while the corresponding value for the wild-type enzyme is 70 degrees C. The three-dimensional structure of the R308K variant has been determined at 3-A resolution. At the high protein concentrations utilized in the crystallizations, this variant exists as a trimer, but weakened salt link interactions are observed for Lys-308.
About this Structure
1WVB is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Subunit-subunit interactions in trimeric arginase. Generation of active monomers by mutation of a single amino acid., Lavulo LT, Sossong TM Jr, Brigham-Burke MR, Doyle ML, Cox JD, Christianson DW, Ash DE, J Biol Chem. 2001 Apr 27;276(17):14242-8. Epub 2001 Jan 24. PMID:11278703 Page seeded by OCA on Sat May 3 14:11:11 2008
