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.


1ix8

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
[[Image:1ix8.gif|left|200px]]
+
{{Seed}}
 +
[[Image:1ix8.png|left|200px]]
<!--
<!--
Line 9: Line 10:
{{STRUCTURE_1ix8| PDB=1ix8 | SCENE= }}
{{STRUCTURE_1ix8| PDB=1ix8 | SCENE= }}
-
'''Aspartate Aminotransferase Active Site Mutant V39F/N194A'''
+
===Aspartate Aminotransferase Active Site Mutant V39F/N194A===
-
==Overview==
+
<!--
-
Aspartate aminotransferase has been known to undergo a significant conformational change, in which the small domain approaches the large domain, and the residues at the entrance of the active site pack together, on binding of substrates. Accompanying this conformational change is a two-unit increase in the pK(a) of the pyridoxal 5'-phosphate-Lys(258) aldimine, which has been proposed to enhance catalysis. To elucidate how the conformational change is coupled to the shift in the aldimine pK(a) and how these changes are involved in catalysis, we analyzed structurally and kinetically an enzyme in which Val(39) located at both the domain interface and the entrance of the active site was replaced with a bulkier residue, Phe. The V39F mutant enzyme showed a more open conformation, and the aldimine pK(a) was lowered by 0.7 unit compared with the wild-type enzyme. When Asn(194) had been replaced by Ala in advance, the V39F mutation did not decrease the aldimine pK(a), showing that the domain rotation controls the aldimine pK(a) via the Arg(386)-Asn(194)-pyridoxal 5'-phosphate linkage system. The maleate-bound V39F enzyme showed the aldimine pK(a) 0.9 unit lower than that of the maleate-bound wild-type enzyme. However, the positions of maleate, Asn(194), and Arg(386) were superimposable between the mutant and the wild-type enzymes; therefore, the domain rotation was not the cause of the lowered aldimine pK(a) value. The maleate-bound V39F enzyme showed an altered side-chain packing pattern in the 37-39 region, and the lack of repulsion between Gly(38) carbonyl O and Tyr(225) Oeta seemed to be the cause of the reduced pK(a) value. Kinetic analysis suggested that the repulsion increases the free energy level of the Michaelis complex and promotes the catalytic reaction.
+
The line below this paragraph, {{ABSTRACT_PUBMED_12488449}}, adds the Publication Abstract to the page
 +
(as it appears on PubMed at http://www.pubmed.gov), where 12488449 is the PubMed ID number.
 +
-->
 +
{{ABSTRACT_PUBMED_12488449}}
==About this Structure==
==About this Structure==
Line 30: Line 34:
[[Category: Nakajima, Y.]]
[[Category: Nakajima, Y.]]
[[Category: Active site mutant]]
[[Category: Active site mutant]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 20:32:07 2008''
+
 
 +
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 14:09:39 2008''

Revision as of 11:09, 1 July 2008

Image:1ix8.png

Template:STRUCTURE 1ix8

Aspartate Aminotransferase Active Site Mutant V39F/N194A

Template:ABSTRACT PUBMED 12488449

About this Structure

1IX8 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Conformational change in aspartate aminotransferase on substrate binding induces strain in the catalytic group and enhances catalysis., Hayashi H, Mizuguchi H, Miyahara I, Nakajima Y, Hirotsu K, Kagamiyama H, J Biol Chem. 2003 Mar 14;278(11):9481-8. Epub 2002 Dec 17. PMID:12488449

Page seeded by OCA on Tue Jul 1 14:09:39 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1ix8"
Personal tools