1ARH

ASPARTATE AMINOTRANSFERASE, Y225R/R386A MUTANT

Summary for 1ARH

• Entry DOI: 10.2210/pdb1arh/pdb
• Descriptor: ASPARTATE AMINOTRANSFERASE, 2-[(3-HYDROXY-2-METHYL-5-PHOSPHONOOXYMETHYL-PYRIDIN-4-YLMETHYLENE)-AMINO]-SUCCINIC ACID (3 entities in total)
• Functional Keywords: transferase (aminotransferase)
• Biological source: Escherichia coli
• Cellular location: Cytoplasm: P00509
• Total number of polymer chains: 2
• Total formula weight: 87782.72

Authors

Malashkevich, V.N.,Jansonius, J.N. (deposition date: 1995-08-23, release date: 1995-11-14, Last modification date: 2024-02-07)

Primary citation

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

PubMed 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.

PubMed: 7556224
DOI: 10.1111/j.1432-1033.1995.tb20861.x

Experimental method

X-RAY DIFFRACTION (2.3 Å)