title: Identification of a Histidine Metal Ligand in the argE-Encoded N-Acetyl-L-Ornithine Deacetylase from Escherichia coli.
abstract: The H355A, H355K, H80A, and H80K mutant enzymes of the argE-encoded N-acetyl-L-ornithine deacetylase (ArgE) from Escherichia coli were prepared, however, only the H355A enzyme was found to be soluble. Kinetic analysis of the Co(II)-loaded H355A exhibited activity levels that were 380-fold less than Co(II)-loaded WT ArgE. Electronic absorption spectra of Co(II)-loaded H355A-ArgE indicate that the bound Co(II) ion resides in a distorted, five-coordinate environment and Isothermal Titration Calorimetry (ITC) data for Zn(II) binding to the H355A enzyme provided a dissociation constant (K d) of 39 μM. A three-dimensional homology model of ArgE was generated using the X-ray crystal structure of the dapE-encoded N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) from Haemophilus influenzae confirming the assignment of H355 as well as H80 as active site ligands.
authors: The Department of Applied Sciences and Mathematics, College of Technology and Innovation, Arizona State University, Mesa, AZ 85212 USA.
authors: Wade C
authors: WC
authors: McGregor
authors: Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL 60626 USA ; The Department of Chemistry, Silesian University of Technology, Gliwice, 44-100 Poland.
authors: Danuta M
authors: DM
authors: Gillner
authors: Contribution from the Department of Chemistry, Marquette University, Milwaukee, WI 53233 USA.
authors: Sabina I
authors: SI
authors: Swierczek
authors: Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL 60626 USA.
authors: Dali
authors: D
authors: Liu
authors: Contribution from the Department of Chemistry, Marquette University, Milwaukee, WI 53233 USA ; Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL 60626 USA.
authors: Richard C
authors: RC
authors: Holz
keywords: Active site ligands; Bioinorganic Chemistry; Deacetylase; Hydrolysis; Isothermal titration calorimetry; Mechanistic enzymology; Zinc