PMID- 17990879
OWN - NLM
STAT- MEDLINE
DCOM- 20080102
LR  - 20071128
IS  - 1520-5126 (Electronic)
IS  - 0002-7863 (Linking)
VI  - 129
IP  - 48
DP  - 2007 Dec 5
TI  - Caldariomyces fumago chloroperoxidase catalyzes the oxidative dehalogenation of 
      chlorophenols by a mechanism involving two one-electron steps.
PG  - 14838-9
AB  - We have employed rapid scan stopped-flow spectroscopy to examine whether the 
      mechanism of oxidative dehalogenation catalyzed by C. fumago chloroperoxidase 
      (CCPO) involves two consecutive one-electron steps or a single two-electron 
      oxidation. First, we optimized the formation of CCPO compound I (CCPO-I) 
      [Fe(IV)=O/porphyrin radical] and CCPO compound II (CCPO-II) [Fe(IV)=O] for use in 
      double mixing rapid scan stopped-flow experiments. Reaction of CCPO-I with 
      2,4,6-trichlorophenol (TCP) quickly yielded CCPO-II. Reaction of CCPO-II, a 
      one-electron oxidant, with TCP rapidly regenerated the ferric resting state of 
      the enzyme. The rates of the reaction of both CCPO-I and -II with TCP are 
      first-order with respect to [TCP]. In the absence of organic substrate, CCPO-I is 
      slowly reduced to CCPO-II and then the ferric state. The ability of both CCPO-I 
      and -II to carry out the oxidative dehalogenation reaction is consistent with a 
      mechanism involving two consecutive one-electron oxidations. In contrast, 
      reaction of CCPO-I with thioanisole generated the ferric enzyme with no evidence 
      of CCPO-II, consistent with a single two-electron oxidation by insertion of an 
      oxygen atom. The relative stability of CCPO-I and -II has allowed us to 
      differentiate between one- and two-electron substrate oxidations using rapid scan 
      stopped-flow techniques.
FAU - Osborne, Robert L
AU  - Osborne RL
AD  - Department of Chemistry and Biochemistry and School of Medicine, University of 
      South Carolina, Columbia, South Carolina 29208, USA.
FAU - Coggins, Michael K
AU  - Coggins MK
FAU - Terner, James
AU  - Terner J
FAU - Dawson, John H
AU  - Dawson JH
LA  - eng
GR  - GM 26730/GM/NIGMS NIH HHS/United States
GR  - GM57042/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20071109
PL  - United States
TA  - J Am Chem Soc
JT  - Journal of the American Chemical Society
JID - 7503056
RN  - 0 (Chlorophenols)
RN  - EC 1.11.1.10 (Chloride Peroxidase)
SB  - IM
MH  - Catalysis
MH  - Chloride Peroxidase/*metabolism
MH  - Chlorophenols/*chemistry/*metabolism
MH  - *Electrons
MH  - Fungi/*enzymology
MH  - Halogenation
MH  - Molecular Structure
MH  - Oxidation-Reduction
MH  - Spectrophotometry
EDAT- 2007/11/10 09:00
MHDA- 2008/01/03 09:00
CRDT- 2007/11/10 09:00
PHST- 2007/11/10 09:00 [pubmed]
PHST- 2008/01/03 09:00 [medline]
PHST- 2007/11/10 09:00 [entrez]
AID - 10.1021/ja0746969 [doi]
PST - ppublish
SO  - J Am Chem Soc. 2007 Dec 5;129(48):14838-9. doi: 10.1021/ja0746969. Epub 2007 Nov 
      9.