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Changing the reaction specificity of a pyridoxal-5'-phosphate-dependent enzyme.


Graber, R; Kasper, P; Malashkevich, V N; Sandmeier, E; Berger, P; Gehring, H; Jansonius, J N; Christen, P (1995). Changing the reaction specificity of a pyridoxal-5'-phosphate-dependent enzyme. FEBS Journal, 232(2):686-690.

Abstract

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.

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.

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Additional indexing

Item Type:Journal Article, refereed
Communities & Collections:04 Faculty of Medicine > Department of Biochemistry
07 Faculty of Science > Department of Biochemistry
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:1 September 1995
Deposited On:11 Feb 2008 12:20
Last Modified:05 Apr 2016 12:17
Publisher:Wiley-Blackwell
ISSN:0014-2956
Publisher DOI:10.1111/j.1432-1033.1995.tb20861.x
PubMed ID:7556224

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