1arh
From Proteopedia
(New page: 200px<br /><applet load="1arh" size="450" color="white" frame="true" align="right" spinBox="true" caption="1arh, resolution 2.3Å" /> '''ASPARTATE AMINOTRANSF...) |
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| - | [[Image:1arh.gif|left|200px]]<br /><applet load="1arh" size=" | + | [[Image:1arh.gif|left|200px]]<br /><applet load="1arh" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1arh, resolution 2.3Å" /> | caption="1arh, resolution 2.3Å" /> | ||
'''ASPARTATE AMINOTRANSFERASE, Y225R/R386A MUTANT'''<br /> | '''ASPARTATE AMINOTRANSFERASE, Y225R/R386A MUTANT'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The electron distribution in the coenzyme-substrate adduct of aspartate | + | The electron distribution in the coenzyme-substrate adduct of aspartate aminotransferase was changed by replacing active-site Arg386 with alanine and introducing a new arginine residue nearby. [Y225R, R386A]Aspartate aminotransferase decarboxylates L-aspartate to L-alanine (kcat = 0.04 s-1), while its transaminase activity towards dicarboxylic amino acids is decreased by three orders of magnitude (kcat = 0.19 s-1). Molecular-dynamics simulations based on the crystal structure of the mutant enzyme suggest that a new hydrogen bond to the imine N atom of the pyridoxal-5'-phosphate- aspartate adduct and an altered electrostatic potential around its beta-carboxylate group underlie the 650,000-fold increase in the ratio of beta-decarboxylase/transaminase activity. |
==About this Structure== | ==About this Structure== | ||
| - | 1ARH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with PPD as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Aspartate_transaminase Aspartate transaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.6.1.1 2.6.1.1] Full crystallographic information is available from [http:// | + | 1ARH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=PPD:'>PPD</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Aspartate_transaminase Aspartate transaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.6.1.1 2.6.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ARH OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Jansonius, J | + | [[Category: Jansonius, J N.]] |
| - | [[Category: Malashkevich, V | + | [[Category: Malashkevich, V N.]] |
[[Category: PPD]] | [[Category: PPD]] | ||
[[Category: transferase (aminotransferase)]] | [[Category: transferase (aminotransferase)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:47:34 2008'' |
Revision as of 09:47, 21 February 2008
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ASPARTATE AMINOTRANSFERASE, Y225R/R386A MUTANT
Overview
The electron distribution in the coenzyme-substrate adduct of aspartate aminotransferase was changed by replacing active-site Arg386 with alanine and introducing a new arginine residue nearby. [Y225R, R386A]Aspartate aminotransferase decarboxylates L-aspartate to L-alanine (kcat = 0.04 s-1), while its transaminase activity towards dicarboxylic amino acids is decreased by three orders of magnitude (kcat = 0.19 s-1). Molecular-dynamics simulations based on the crystal structure of the mutant enzyme suggest that a new hydrogen bond to the imine N atom of the pyridoxal-5'-phosphate- aspartate adduct and an altered electrostatic potential around its beta-carboxylate group underlie the 650,000-fold increase in the ratio of beta-decarboxylase/transaminase activity.
About this Structure
1ARH is a Single protein structure of sequence from Escherichia coli with as ligand. Active as Aspartate transaminase, with EC number 2.6.1.1 Full crystallographic information is available from OCA.
Reference
Changing the reaction specificity of a pyridoxal-5'-phosphate-dependent enzyme., Graber R, Kasper P, Malashkevich VN, Sandmeier E, Berger P, Gehring H, Jansonius JN, Christen P, Eur J Biochem. 1995 Sep 1;232(2):686-90. PMID:7556224
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