1j0c
From Proteopedia
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ACC deaminase mutated to catalytic residue
Overview
The pyridoxal 5'-phosphate-dependent enzymes have been evolved to catalyze, diverse substrates and to cause the reaction to vary., 1-Aminocyclopropane-1-carboxylate deaminase catalyzes the cyclopropane, ring-opening reaction followed by deamination specifically. Since it was, discovered in 1978, the enzyme has been widely investigated from the, mechanistic and physiological viewpoints because the substrate is a, precursor of the plant hormone ethylene and the enzymatic reaction, includes a cyclopropane ring-opening. We have previously reported the, crystal structure of the native enzyme. Here we report the crystal, structures of the two reaction intermediates created by the mutagenesis, complexed with the substrate. The substrate was validated in the active, site of two forms: 1). covalent-bonded external aldimine with the coenzyme, in the K51T form and 2). the non-covalent interaction around the coenzyme, in the Y295F form. The orientations of the substrate in both structures, were quite different form each other. In concert with other site-specific, mutation experiments, this experiment revealed the ingenious and unique, strategies that are used to achieve the specific activity. The substrate, incorporated into the active site is reactivated by a two-phenol charge, relay system to lead to the formation of a Schiff base with the coenzyme., The catalytic Lys51 residue may play a novel role to abstract the, methylene proton from the substrate in cooperation with other factors, the, carboxylate group of the substrate and the electron-adjusting apparatuses, of the coenzyme.
About this Structure
1J0C is a Single protein structure of sequence from Williopsis saturnus with PLP as ligand. Active as 1-aminocyclopropane-1-carboxylate deaminase, with EC number 3.5.99.7 Full crystallographic information is available from OCA.
Reference
Reaction intermediate structures of 1-aminocyclopropane-1-carboxylate deaminase: insight into PLP-dependent cyclopropane ring-opening reaction., Ose T, Fujino A, Yao M, Watanabe N, Honma M, Tanaka I, J Biol Chem. 2003 Oct 17;278(42):41069-76. Epub 2003 Jul 26. PMID:12882962
Page seeded by OCA on Tue Nov 20 17:49:30 2007
