1hqx
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R308K ARGINASE VARIANT
OverviewOverview
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 StructureAbout this Structure
1HQX is a Single protein structure of sequence from Rattus norvegicus with MN as ligand. Active as Arginase, with EC number 3.5.3.1 Full crystallographic information is available from OCA.
ReferenceReference
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 Tue Nov 20 16:45:49 2007