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Major changes in copper coordination accompany reduction of peptidylglycine monooxygenase: implications for electron transfer and the catalytic mechanism
- Source :
- JBIC Journal of Biological Inorganic Chemistry. 5:341-353
- Publication Year :
- 2000
- Publisher :
- Springer Science and Business Media LLC, 2000.
-
Abstract
- X-ray absorption spectroscopy has been used to probe the local coordination of the copper centers in the oxidized and reduced states of the peptidylglycine monooxygenase catalytic core (PHMcc) in both the resting and substrate-bound forms of the enzyme. The results indicate that reduction causes significant changes in coordination number and geometry of both Cu centers (CuH and CuM). The CuH center changes from 4- or 5-coordinate tetragonal to a 2-coordinate configuration, with one of the three histidine ligands becoming undetectable by EXAFS (suggesting that it has moved away from the CuH by at least 0.3 A). The CuM center changes from 4- or 5-coordinate tetragonal to a trigonal or tetrahedral configuration, with an estimated 0.3-0.5 A movement of the M314 S ligand. Reduction also leads to loss of coordinated water from both of the coppers. Substrate binding has little or no effect on the local environment of the Cu centers in either oxidation state. These findings bring into question whether direct electron transfer between CuH and CuM via a tunneling mechanism can be fast enough to support the observed catalytic rate, and suggest that some other mechanism for electron transfer, such as superoxide channeling, should be considered.
- Subjects :
- Coordination number
Peptidylglycine monooxygenase
chemistry.chemical_element
CHO Cells
Photochemistry
Biochemistry
Mixed Function Oxygenases
Substrate Specificity
Catalysis
Electron Transport
Inorganic Chemistry
Electron transfer
Multienzyme Complexes
Oxidation state
Cricetinae
Animals
Binding Sites
Extended X-ray absorption fine structure
Chemistry
Ligand
X-Rays
Models, Theoretical
Copper
Recombinant Proteins
Oxidation-Reduction
Subjects
Details
- ISSN :
- 14321327 and 09498257
- Volume :
- 5
- Database :
- OpenAIRE
- Journal :
- JBIC Journal of Biological Inorganic Chemistry
- Accession number :
- edsair.doi.dedup.....9cccce8201d8c848f5d01bddd8f49b0d
- Full Text :
- https://doi.org/10.1007/pl00010663