1did
From Proteopedia
(New page: 200px<br /><applet load="1did" size="450" color="white" frame="true" align="right" spinBox="true" caption="1did, resolution 2.5Å" /> '''OBSERVATIONS OF REACT...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:1did.jpg|left|200px]]<br /><applet load="1did" size=" | + | [[Image:1did.jpg|left|200px]]<br /><applet load="1did" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1did, resolution 2.5Å" /> | caption="1did, resolution 2.5Å" /> | ||
'''OBSERVATIONS OF REACTION INTERMEDIATES AND THE MECHANISM OF ALDOSE-KETOSE INTERCONVERSION BY D-XYLOSE ISOMERASE'''<br /> | '''OBSERVATIONS OF REACTION INTERMEDIATES AND THE MECHANISM OF ALDOSE-KETOSE INTERCONVERSION BY D-XYLOSE ISOMERASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Crystallographic studies of D-xylose isomerase (D-xylose ketol-isomerase, EC 5.3.1.5) incubated to equilibrium with substrate/product mixtures of | + | Crystallographic studies of D-xylose isomerase (D-xylose ketol-isomerase, EC 5.3.1.5) incubated to equilibrium with substrate/product mixtures of xylose and xylulose show electron density for a bound intermediate. The accumulation of this bound intermediate shows that the mechanism is a non-Michaelis type. Carrell et al. [Carrell, H. L., Glusker, J. P., Burger, V., Manfre, F., Tritsch, D. & Biellmann, J.-F. (1989) Proc. Natl. Acad. Sci. USA 86, 4440-4444] and the present authors studied crystals of the enzyme-substrate complex under different conditions and made different interpretations of the substrate density, leading to different conclusions about the enzyme mechanism. All authors agree that the bound intermediate of the sugar is in an open-chain form. It is suggested that the higher-temperature study of Carrell et al. may have produced an equilibrium of multiple states, whose density fits poorly to the open-chain substrate, and led to incorrect interpretation. The two groups also bound different closed-ring sugar analogues to the enzyme, but these analogues bind differently. A possible explanation consistent with all the data is that the enzyme operates by a hydride shift mechanism. |
==About this Structure== | ==About this Structure== | ||
| - | 1DID is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arthrobacter_sp. Arthrobacter sp.] with DIG and MN as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Xylose_isomerase Xylose isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.5 5.3.1.5] Full crystallographic information is available from [http:// | + | 1DID is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arthrobacter_sp. Arthrobacter sp.] with <scene name='pdbligand=DIG:'>DIG</scene> and <scene name='pdbligand=MN:'>MN</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Xylose_isomerase Xylose isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.5 5.3.1.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DID OCA]. |
==Reference== | ==Reference== | ||
| Line 14: | Line 14: | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Xylose isomerase]] | [[Category: Xylose isomerase]] | ||
| - | [[Category: Blow, D | + | [[Category: Blow, D M.]] |
| - | [[Category: Collyer, C | + | [[Category: Collyer, C A.]] |
| - | [[Category: Goldberg, J | + | [[Category: Goldberg, J D.]] |
[[Category: DIG]] | [[Category: DIG]] | ||
[[Category: MN]] | [[Category: MN]] | ||
[[Category: isomerase(intramolecular oxidoreductse)]] | [[Category: isomerase(intramolecular oxidoreductse)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:16:50 2008'' |
Revision as of 10:16, 21 February 2008
|
OBSERVATIONS OF REACTION INTERMEDIATES AND THE MECHANISM OF ALDOSE-KETOSE INTERCONVERSION BY D-XYLOSE ISOMERASE
Overview
Crystallographic studies of D-xylose isomerase (D-xylose ketol-isomerase, EC 5.3.1.5) incubated to equilibrium with substrate/product mixtures of xylose and xylulose show electron density for a bound intermediate. The accumulation of this bound intermediate shows that the mechanism is a non-Michaelis type. Carrell et al. [Carrell, H. L., Glusker, J. P., Burger, V., Manfre, F., Tritsch, D. & Biellmann, J.-F. (1989) Proc. Natl. Acad. Sci. USA 86, 4440-4444] and the present authors studied crystals of the enzyme-substrate complex under different conditions and made different interpretations of the substrate density, leading to different conclusions about the enzyme mechanism. All authors agree that the bound intermediate of the sugar is in an open-chain form. It is suggested that the higher-temperature study of Carrell et al. may have produced an equilibrium of multiple states, whose density fits poorly to the open-chain substrate, and led to incorrect interpretation. The two groups also bound different closed-ring sugar analogues to the enzyme, but these analogues bind differently. A possible explanation consistent with all the data is that the enzyme operates by a hydride shift mechanism.
About this Structure
1DID is a Single protein structure of sequence from Arthrobacter sp. with and as ligands. Active as Xylose isomerase, with EC number 5.3.1.5 Full crystallographic information is available from OCA.
Reference
Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase., Collyer CA, Blow DM, Proc Natl Acad Sci U S A. 1990 Feb;87(4):1362-6. PMID:2304904
Page seeded by OCA on Thu Feb 21 12:16:50 2008
