title: Catalytic efficiency of dehaloperoxidase A is controlled by electrostatics--application of the vibrational Stark effect to understand enzyme kinetics.
abstract: The vibrational Stark effect is gaining popularity as a method for probing electric fields in proteins. In this work, we employ it to explain the effect of single charge mutations in dehaloperoxidase-hemoglobin A (DHP A) on the kinetics of the enzyme. In a previous communication published in this journal (BBRC 2012, 420, 733-737) it has been shown that an increase in the overall negative charge of DHP A through mutation causes a decrease in its catalytic efficiency. Here, by labeling the protein with 4-mercaptobenzonitrile (MBN), a Stark probe molecule, we provide further evidence that the diffusion control of the catalytic process arises from the electrostatic repulsion between the enzyme and the negatively charged substrate. The linear correlation observed between the nitrile stretching frequency of the protein-bound MBN and the catalytic efficiency of the single-site mutants of the enzyme indicates that electrostatic interactions play a dominant role in determining the catalytic efficiency of DHP A.
authors.affiliation: Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße des 17, Juni 135, D-10623 Berlin, Germany.
authors.forename: Gal
authors.initials: G
authors.lastname: Schkolnik
authors.forename: Tillmann
authors.initials: T
authors.lastname: Utesch
authors.forename: Junjie
authors.initials: J
authors.lastname: Zhao
authors.forename: Shu
authors.initials: S
authors.lastname: Jiang
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Thompson
authors.forename: Maria-Andrea
authors.initials: MA
authors.lastname: Mroginski
authors.forename: Peter
authors.initials: P
authors.lastname: Hildebrandt
authors.forename: Stefan
authors.initials: S
authors.lastname: Franzen
mesh_terms: D000818:Animals; D002384:Catalysis; D007700:Kinetics; D009154:Mutation; D009195:Peroxidase / Q000737:chemistry* / Q000235:genetics; D010544:Peroxidases / Q000737:chemistry* / Q000235:genetics; D011077:Polychaeta / Q000201:enzymology*; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity; D014732:Vibration
chemical_list: D010544:Peroxidases; D009195:Peroxidase