1cqs

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|SITE=
|SITE=
|LIGAND= <scene name='pdbligand=EQU:EQUILENIN'>EQU</scene>
|LIGAND= <scene name='pdbligand=EQU:EQUILENIN'>EQU</scene>
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|ACTIVITY= [http://en.wikipedia.org/wiki/Steroid_Delta-isomerase Steroid Delta-isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.3.1 5.3.3.1]
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|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Steroid_Delta-isomerase Steroid Delta-isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.3.1 5.3.3.1] </span>
|GENE=
|GENE=
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|DOMAIN=
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|RELATEDENTRY=[[1opy|1OPY]]
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|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1cqs FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1cqs OCA], [http://www.ebi.ac.uk/pdbsum/1cqs PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1cqs RCSB]</span>
}}
}}
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[[Category: Oh, B H.]]
[[Category: Oh, B H.]]
[[Category: Park, S.]]
[[Category: Park, S.]]
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[[Category: EQU]]
 
[[Category: equilenin]]
[[Category: equilenin]]
[[Category: ksi]]
[[Category: ksi]]
[[Category: putida lbhb]]
[[Category: putida lbhb]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 10:27:44 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 19:26:43 2008''

Revision as of 16:26, 30 March 2008

Image:1cqs.gif


PDB ID 1cqs

Drag the structure with the mouse to rotate
, resolution 1.90Å
Ligands:
Activity: Steroid Delta-isomerase, with EC number 5.3.3.1
Related: 1OPY


Resources: FirstGlance, OCA, PDBsum, RCSB
Coordinates: save as pdb, mmCIF, xml



CRYSTAL STRUCTURE OF D103E MUTANT WITH EQUILENINEOF KSI IN PSEUDOMONAS PUTIDA


Overview

Delta 5-3-ketosteroid isomerase (KSI) catalyzes the allylic isomerization of Delta 5-3-ketosteroids at a rate approaching the diffusion limit by an intramolecular transfer of a proton. Despite the extensive studies on the catalytic mechanism, it still remains controversial whether the catalytic residue Asp-99 donates a hydrogen bond to the steroid or to Tyr-14. To clarify the role of Asp-99 in the catalysis, two single mutants of D99E and D99L and three double mutants of Y14F/D99E, Y14F/D99N, and Y14F/D99L have been prepared by site-directed mutagenesis. The D99E mutant whose side chain at position 99 is longer by an additional methylene group exhibits nearly the same kcat as the wild-type while the D99L mutant exhibits ca. 125-fold lower kcat than that of the wild-type. The mutations made at positions 14 and 99 exert synergistic or partially additive effect on kcat in the double mutants, which is inconsistent with the mechanism based on the hydrogen-bonded catalytic dyad, Asp-99 COOH...Tyr-14 OH...C3-O of the steroid. The crystal structure of D99E/D38N complexed with equilenin, an intermediate analogue, at 1.9 A resolution reveals that the distance between Tyr-14 O eta and Glu-99 O epsilon is ca. 4.2 A, which is beyond the range for a hydrogen bond, and that the distance between Glu-99 O epsilon and C3-O of the steroid is maintained to be ca. 2.4 A, short enough for a hydrogen bond to be formed. Taken together, these results strongly support the idea that Asp-99 contributes to the catalysis by donating a hydrogen bond directly to the intermediate.

About this Structure

1CQS is a Single protein structure of sequence from Pseudomonas putida. Full crystallographic information is available from OCA.

Reference

Asp-99 donates a hydrogen bond not to Tyr-14 but to the steroid directly in the catalytic mechanism of Delta 5-3-ketosteroid isomerase from Pseudomonas putida biotype B., Choi G, Ha NC, Kim SW, Kim DH, Park S, Oh BH, Choi KY, Biochemistry. 2000 Feb 8;39(5):903-9. PMID:10653633

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