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.


1z9a

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
[[Image:1z9a.gif|left|200px]]
+
{{Seed}}
 +
[[Image:1z9a.png|left|200px]]
<!--
<!--
Line 9: Line 10:
{{STRUCTURE_1z9a| PDB=1z9a | SCENE= }}
{{STRUCTURE_1z9a| PDB=1z9a | SCENE= }}
-
'''Crystal Structure Of The Asn-309 To Asp Mutant Of Candida Tenuis Xylose Reductase (Akr2B5) Bound To Nad+'''
+
===Crystal Structure Of The Asn-309 To Asp Mutant Of Candida Tenuis Xylose Reductase (Akr2B5) Bound To Nad+===
-
==Overview==
+
<!--
-
Little is known about how substrates bind to CtXR (Candida tenuis xylose reductase; AKR2B5) and other members of the AKR (aldo-keto reductase) protein superfamily. Modelling of xylose into the active site of CtXR suggested that Trp23, Asp50 and Asn309 are the main components of pentose-specific substrate-binding recognition. Kinetic consequences of site-directed substitutions of these residues are reported. The mutants W23F and W23Y catalysed NADH-dependent reduction of xylose with only 4 and 1% of the wild-type efficiency (kcat/K(m)) respectively, but improved the wild-type selectivity for utilization of ketones, relative to xylose, by factors of 156 and 471 respectively. Comparison of multiple sequence alignment with reported specificities of AKR members emphasizes a conserved role of Trp23 in determining aldehyde-versus-ketone substrate selectivity. D50A showed 31 and 18% of the wild-type catalytic-centre activities for xylose reduction and xylitol oxidation respectively, consistent with a decrease in the rates of the chemical steps caused by the mutation, but no change in the apparent substrate binding constants and the pattern of substrate specificities. The 30-fold preference of the wild-type for D-galactose compared with 2-deoxy-D-galactose was lost completely in N309A and N309D mutants. Comparison of the 2.4 A (1 A=0.1 nm) X-ray crystal structure of mutant N309D bound to NAD+ with the previous structure of the wild-type holoenzyme reveals no major structural perturbations. The results suggest that replacement of Asn309 with alanine or aspartic acid disrupts the function of the original side chain in donating a hydrogen atom for bonding with the substrate C-2(R) hydroxy group, thus causing a loss of transition-state stabilization energy of 8-9 kJ/mol.
+
The line below this paragraph, {{ABSTRACT_PUBMED_16336198}}, adds the Publication Abstract to the page
 +
(as it appears on PubMed at http://www.pubmed.gov), where 16336198 is the PubMed ID number.
 +
-->
 +
{{ABSTRACT_PUBMED_16336198}}
==About this Structure==
==About this Structure==
Line 34: Line 38:
[[Category: Substrate selectivity]]
[[Category: Substrate selectivity]]
[[Category: Xylose reductase]]
[[Category: Xylose reductase]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:20:30 2008''
+
 
 +
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 22:55:07 2008''

Revision as of 19:55, 27 July 2008

Image:1z9a.png

Template:STRUCTURE 1z9a

Crystal Structure Of The Asn-309 To Asp Mutant Of Candida Tenuis Xylose Reductase (Akr2B5) Bound To Nad+

Template:ABSTRACT PUBMED 16336198

About this Structure

1Z9A is a Single protein structure of sequence from Candida tenuis. Full crystallographic information is available from OCA.

Reference

Probing the substrate binding site of Candida tenuis xylose reductase (AKR2B5) with site-directed mutagenesis., Kratzer R, Leitgeb S, Wilson DK, Nidetzky B, Biochem J. 2006 Jan 1;393(Pt 1):51-8. PMID:16336198

Page seeded by OCA on Sun Jul 27 22:55:07 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1z9a"
Personal tools