Document Detail


H-atom abstraction reaction for organic substrates via mononuclear copper(II)-superoxo species as a model for DbetaM and PHM.
MedLine Citation:
PMID:  18399242     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Hydrogen atom abstraction reactions have been implicated in oxygenation reactions catalyzed by copper monooxygenases such as peptidylglycine alpha-hydroxylating monooxygenase (PHM) and dopamine beta-monooxygenase (DbetaM). We have investigated mononuclear copper(I) and copper(II) complexes with bis[(6-neopentylamino-2-pyridyl)methyl][(2-pyridyl)methyl]amine (BNPA) as functional models for these enzymes. The reaction of [Cu(II)(bnpa)]2+ with H2O2, affords a quasi-stable mononuclear copper(II)-hydroperoxo complex, [Cu(II)(bnpa)(OOH)]+ (4) which is stabilized by hydrophobic interactions and hydrogen bonds in the vicinity of the copper(II) ion. On the other hand, the reaction of [Cu(I)(bnpa)]+ (1) with O2 generates a trans-mu-1,2-peroxo dicopper(II) complex [Cu(II)2(bnpa)2(O2(2-]2+ (2). Interestingly, the same reactions carried out in the presence of exogenous substrates such as TEMPO-H, produce a mononuclear copper(II)-hydroperoxo complex 4. Under these conditions, the H-atom abstraction reaction proceeds via the mononuclear copper(II)-superoxo intermediate [Cu(II)(bnpa)(O2-)]+ (3), as confirmed from indirect observations using a spin trap reagent. Reactions with several substrates having different bond dissociation energies (BDE) indicate that, under our experimental conditions the H-atom abstraction reaction proceeds for substrates with a weak X-H bond (BDE < 72.6 kcal mol(-1)). These investigations indicate that the copper(II)-hydroperoxo complex is a useful tool for elucidation of H-atom abstraction reaction mechanisms for exogenous substrates. The useful functionality of the complex has been achieved via careful control of experimental conditions and the choice of appropriate ligands for the complex.
Authors:
Tatsuya Fujii; Syuhei Yamaguchi; Shun Hirota; Hideki Masuda
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Dalton transactions (Cambridge, England : 2003)     Volume:  -     ISSN:  1477-9226     ISO Abbreviation:  Dalton Trans     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2008-04-10     Completed Date:  2008-04-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101176026     Medline TA:  Dalton Trans     Country:  England    
Other Details:
Languages:  eng     Pagination:  164-70     Citation Subset:  IM    
Affiliation:
Department of Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Catalysis
Copper / chemistry*
Dopamine beta-Hydroxylase / chemistry*
Hydrogen / chemistry*
Ligands
Mixed Function Oxygenases / chemistry*
Molecular Structure
Multienzyme Complexes / chemistry*
Organometallic Compounds / chemical synthesis,  chemistry*
Oxygen / chemistry*
Spectrophotometry, Ultraviolet
Spectrum Analysis, Raman
Substrate Specificity
Chemical
Reg. No./Substance:
0/Ligands; 0/Multienzyme Complexes; 0/Organometallic Compounds; 1333-74-0/Hydrogen; 7440-50-8/Copper; 7782-44-7/Oxygen; EC 1.-/Mixed Function Oxygenases; EC 1.14.17.1/Dopamine beta-Hydroxylase; EC 1.14.17.3/peptidylglycine monooxygenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Mixed ligand ruthenium(II) complexes of bis(pyrid-2-yl)-/bis(benzimidazol-2-yl)-dithioether and diim...
Next Document:  Speed constancy and the perception of distance.