This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.

Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.


2ri6

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
[[Image:2ri6.jpg|left|200px]]
+
{{Seed}}
 +
[[Image:2ri6.png|left|200px]]
<!--
<!--
Line 9: Line 10:
{{STRUCTURE_2ri6| PDB=2ri6 | SCENE= }}
{{STRUCTURE_2ri6| PDB=2ri6 | SCENE= }}
-
'''Crystal Structure of S112A mutant of a C-C hydrolase, BphD from Burkholderia xenovorans LB400'''
+
===Crystal Structure of S112A mutant of a C-C hydrolase, BphD from Burkholderia xenovorans LB400===
-
==Overview==
+
<!--
-
BphD of Burkholderia xenovorans LB400 catalyzes an unusual C-C bond hydrolysis of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) to afford benzoic acid and 2-hydroxy-2,4-pentadienoic acid (HPD). An enol-keto tautomerization has been proposed to precede hydrolysis via a gem-diol intermediate. The role of the canonical catalytic triad (Ser-112, His-265, Asp-237) in mediating these two half-reactions remains unclear. We previously reported that the BphD-catalyzed hydrolysis of HOPDA (lambda(max) is 434 nm for the free enolate) proceeds via an unidentified intermediate with a red-shifted absorption spectrum (lambda(max) is 492 nm) (Horsman, G. P., Ke, J., Dai, S., Seah, S. Y. K., Bolin, J. T., and Eltis, L. D. (2006) Biochemistry 45, 11071-11086). Here we demonstrate that the S112A variant generates and traps a similar intermediate (lambda(max) is 506 nm) with a similar rate, 1/tau approximately 500 s(-1). The crystal structure of the S112A:HOPDA complex at 1.8-A resolution identified this intermediate as the keto tautomer, (E)-2,6-dioxo-6-phenyl-hex-3-enoate. This keto tautomer did not accumulate in either the H265A or the S112A/H265A double variants, indicating that His-265 catalyzes tautomerization. Consistent with this role, the wild type and S112A enzymes catalyzed tautomerization of the product HPD, whereas H265A variants did not. This study thus identifies a keto intermediate, and demonstrates that the catalytic triad histidine catalyzes the tautomerization half-reaction, expanding the role of this residue from its purely hydrolytic function in other serine hydrolases. Finally, the S112A:HOPDA crystal structure is more consistent with hydrolysis occurring via an acyl-enzyme intermediate than a gem-diol intermediate as solvent molecules have poor access to C6, and the closest ordered water is 7 A away.
+
The line below this paragraph, {{ABSTRACT_PUBMED_17442675}}, adds the Publication Abstract to the page
 +
(as it appears on PubMed at http://www.pubmed.gov), where 17442675 is the PubMed ID number.
 +
-->
 +
{{ABSTRACT_PUBMED_17442675}}
==About this Structure==
==About this Structure==
Line 27: Line 31:
[[Category: C-c bond hydrolase]]
[[Category: C-c bond hydrolase]]
[[Category: Hydrolase]]
[[Category: Hydrolase]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 16:57:00 2008''
+
 
 +
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 04:28:15 2008''

Revision as of 01:28, 29 July 2008

Image:2ri6.png

Template:STRUCTURE 2ri6

Crystal Structure of S112A mutant of a C-C hydrolase, BphD from Burkholderia xenovorans LB400

Template:ABSTRACT PUBMED 17442675

About this Structure

2RI6 is a Single protein structure of sequence from Burkholderia xenovorans. This structure supersedes the now removed PDB entry 2pu6. Full crystallographic information is available from OCA.

Reference

The tautomeric half-reaction of BphD, a C-C bond hydrolase. Kinetic and structural evidence supporting a key role for histidine 265 of the catalytic triad., Horsman GP, Bhowmik S, Seah SY, Kumar P, Bolin JT, Eltis LD, J Biol Chem. 2007 Jul 6;282(27):19894-904. Epub 2007 Apr 18. PMID:17442675

Page seeded by OCA on Tue Jul 29 04:28:15 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/2ri6"
Personal tools