Characterization of a Bromoperoxidase From the Marine Algae Penicillus Capitatus
Manthey, John Anthony
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/70537
Description
Title
Characterization of a Bromoperoxidase From the Marine Algae Penicillus Capitatus
Author(s)
Manthey, John Anthony
Issue Date
1984
Department of Study
Biochemistry
Discipline
Biochemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biophysics, General
Abstract
The soluble emzyme bromperoxidase isolated from the marine green algae P. capitatus is capable of catalyzing halide oxiations while in the presence of peroxide. Protein purification and characterization of this enzyme showed that the prosthetic group is ferric protoporphyrin IX and that the enzyme consists of two equal molecular weight subunits whose combined weight is approximately 100,000. Bromoperoxidase contains no detectable level of carbohydrate.
Initial characterization of the oxidized intermediates of bromoperoxidase which result from the protein's reaction with peroxide molecules shows that bromoperoxidase forms typical Compound I and Compound II species. Electron para-magnetic resonance (EPR) measurements failed to show any radical signal associated with Compound I. A third oxidized intermediate, termed Compound III forms as a result of the reaction of peroxide with Compound II or as a reaction product of an oxidase-type reaction involving dihydroxyfumaric acid.
Characterization of the catalytic parameters of bromoperoxidase showed that the enzyme is capable of catalyzing chloride, bromide and iodide ion oxidation. The bromide and iodide oxidation reactions follow similar pH-rate profile equations and have pH optima near ph 6-7. Chloride oxidations follow a second pH-rate profile equation and have pH optima near pH 4. Kinetics of bromide ion oxidation demonstrated that monochlorodimedone (MCD) bromination catalyzed by bromoperoxidase involves tribromide ion formation. The bromide enhanced catalase-type reaction resulting from the catalytic degradation of hydrogen peroxide by bromoperoxidase was also shown to involve tribromide ion formation. Chloride ion oxidation was demonstrated by the isolation of labeled {('36)Cl}-dichlorodimedone synthesized by bromoperoxidase, MCD, peroxide, and Na('36)Cl. Similar chloride enhanced reactions were observed for 2-thiouracil oxidation and the catalase-type reaction. Compound III accumulates during the peroxidative and MCD bromination reactions catalyzed by bromoperoxidase. The accumulation of Compound III greatly affects the reaction rates for the above reactions.
Studies of the ferrous state of bromoperoxidase demonstrated that the enzyme exists as two reduced forms. Similar behavior was observed for the ferrous-carbonmonoxy complexes as well. The ferrous-carbonmonoixy complexes did not show a P-450 type spectrum but rather spectra similar to those observed for peroxidases containing a proximal imidazole ligand. Stepwise reductions of bromoperoxidase showed complicated reduction properties for the enzyme.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
