The 3.0 A crystal structure of xylose isomerase from Streptomyces olivochromogenes |
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Authors: | Farber Gregory K; Petsko Gregory A; Ringe Dagmar |
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Affiliation: | Department of Chemistry, Massachusetts Institute of Technology Cambridge. MA 02139, USA |
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Abstract: | The crystal structure of xylose isomerase E.C. 5.3.1.5
EC]
] fromStreptomyces olivochromogenes has been determined to 3.0 Åresolution. The crystals belong to space group P22121 with unitcell parameters a = 98.7, b = 93.9, c = 87.7. The asymmetricunit contains half of a tetrameric molecule of 222 symmetry.The two-fold axis relating the two molecules in the asymmetricunit is close to where a crystallographic two-fold would beif the space group were 1222. This causes the diffraction patternto have strong 1222 pseudo-symmetry, so all data were collectedin this pseudo-space group. Since the sequence of this enzymehas not been reported, a polyalanine backbone has been fittedto the electron density. Xylose isomerase has two domains: theN-terminal domain is an eight-stranded /ß barrel of299 residues. The C-terminal domain is a large loop of 50 residueswhich is involved in inter-molecular contacts. Comparison ofxylose isomerase with the archetypical /ß barrel protein,triose phosphate isomerase, reveals that the proteins overlapbest when the third ( ß) strand of xylose isomeraseis superimposed on the first ( ß) strand of triosephosphate isomerase. This same overlap has also been found betweenthe muconate lactonising enzyme and triose phosphate isomeraseGoldman et al. (1987) J. Mol. Biol., in press]. |
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Keywords: | /" target="_blank">gif" ALT="{alpha}" BORDER="0">/ ß / barrels/ crystal structure/ glucose isomerase/ xylose isomerase |
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