1b06

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spinqualitylabelsall models 1b06, resolution 2.2Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

SUPEROXIDE DISMUTASE FROM SULFOLOBUS ACIDOCALDARIUS

Overview

The extremely thermostable superoxide dismutase from the hyperthermophilic, archaeon Sulfolobus acidocaldarius was crystallized and the, three-dimensional structure was determined by X-ray diffraction methods., The enzyme crystallized in the monoclinic spacegroup C2 with the cell, dimensions a=168.1 A, b=91.3 A, c=85.7 A, beta=91.4 degrees. The, diffraction limit of these crystals was 2.2 A. The crystals were very, stable in the X-ray beam and measured diffraction data of a single crystal, had a completeness of 99.5 % up to a resolution of 2.2 A.The crystal, structure of S. acidocaldarius superoxide dismutase was solved by, Patterson search methods using a dimer of Thermus thermophilus superoxide, dismutase as a search model. The asymmetric unit accommodates three, dimers. Two dimers form a tetramer by using only local symmetries; the, third dimer forms a tetramer as well, however, by using the, crystallographic 2-fold symmetry.The three-dimensional structure of the S., acidocaldarius dismutase has typical features of tetrameric dismutases., Secondary structure elements as well as residues important for the, catalytic activity of the enzyme were found to be highly conserved. The, model was refined at a resolution of 2.2 A and yielded a crystallographic, R-value of 17.4 % (Rfree=22.3 %). A structural comparison of the two, extremely stable tetrameric dismutases from S. acidocaldarius and Aquifex, pyrophilus with the less stable enzyme from T. thermophilus and Mycoplasma, tuberculosis revealed the structural determinants which are probably, responsible for the high intrinsic stability of S. acidocaldarius, dismutase. The most obvious factor which may give rise to the, extraordinary thermal stability of S. acidocaldarius dismutase (melting, temperature of about 125 degreesC) is the increase in intersubunit ion, pairs and hydrogen bonds and, more importantly, the significant reduction, of solvent-accessible hydrophobic surfaces, as well as an increase in the, percentage of buried hydrophobic residues.

About this Structure

1B06 is a Single protein structure of sequence from Sulfolobus acidocaldarius with FE as ligand. Active as Superoxide dismutase, with EC number 1.15.1.1 Full crystallographic information is available from OCA.

Reference

Refined crystal structure of a superoxide dismutase from the hyperthermophilic archaeon Sulfolobus acidocaldarius at 2.2 A resolution., Knapp S, Kardinahl S, Hellgren N, Tibbelin G, Schafer G, Ladenstein R, J Mol Biol. 1999 Jan 15;285(2):689-702. PMID:9878438

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