PMID- 23952341
OWN - NLM
STAT- MEDLINE
DCOM- 20140211
LR  - 20131210
IS  - 1520-4995 (Electronic)
IS  - 0006-2960 (Linking)
VI  - 52
IP  - 36
DP  - 2013 Sep 10
TI  - Complexes of dual-function hemoglobin/dehaloperoxidase with substrate 
      2,4,6-trichlorophenol are inhibitory and indicate binding of halophenol to 
      compound I.
PG  - 6203-10
LID - 10.1021/bi400627w [doi]
AB  - The hemoglobin of sea worm Amphitrite ornata, which for historical reasons is 
      abbreviated as DHP for dehaloperoxidase, has two physiological functions: it 
      binds dioxygen in the ferrous state and dehalogenates halophenols, such as 
      2,4,6-trichlorophenol (TCP), using hydrogen peroxide as the oxidant in the ferric 
      state. The crystal structures of three DHP variants (Y34N, Y34N/S91G, and L100F) 
      with TCP bound show two mutually exclusive modes of substrate binding. One of 
      them, the internal site, is deep inside the distal pocket with the phenolic OH 
      moiety forming a hydrogen bond to the water molecule coordinated to the heme Fe. 
      In this complex, the distal histidine is predominantly located in the closed 
      position and also forms a hydrogen bond to the phenolic hydroxide. The second 
      mode of TCP binding is external, at the heme edge, with the halophenol molecule 
      forming a lid covering the entrance to the distal cavity. The distal histidine is 
      in the open position and forms a hydrogen bond to the OH group of TCP, which also 
      hydrogen bonds to the hydroxyl of Tyr38. The distance between the Cl4 atom of TCP 
      and the heme Fe is 3.9 A (nonbonding). In both complexes, TCP molecules prevent 
      the approach of hydrogen peroxide to the heme, indicating that the complexes are 
      inhibitory and implying that the substrates must bind in an ordered fashion: 
      hydrogen peroxide first and TCP second. Kinetic studies confirmed the inhibition 
      of DHP by high concentrations of TCP. The external binding mode may resemble the 
      interaction of TCP with Compound I, the catalytic intermediate to which 
      halophenols bind. The measured values of the apparent Km for TCP were in the 
      range of 0.3-0.8 mM, much lower than the concentrations required to observe TCP 
      binding in crystals. This indicates that during catalysis TCP binds to Compound 
      I. Mutant F21W, which likely has the internal TCP binding site blocked, has ~7% 
      of the activity of wild-type DHP.
FAU - Wang, Chunxue
AU  - Wang C
AD  - Department of Chemistry and Biochemistry, University of South Carolina , 
      Columbia, South Carolina 29208, United States.
FAU - Lovelace, Leslie L
AU  - Lovelace LL
FAU - Sun, Shengfang
AU  - Sun S
FAU - Dawson, John H
AU  - Dawson JH
FAU - Lebioda, Lukasz
AU  - Lebioda L
LA  - eng
SI  - PDB/4KMV
SI  - PDB/4KMW
SI  - PDB/4KN3
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20130829
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Chlorophenols)
RN  - 0 (Hemoglobins)
RN  - EC 1.11.1.- (Peroxidases)
RN  - MHS8C5BAUZ (2,4,6-trichlorophenol)
SB  - IM
MH  - Animals
MH  - Binding Sites
MH  - Catalysis
MH  - Chlorophenols/*metabolism/pharmacology
MH  - Crystallography, X-Ray
MH  - Hemoglobins/antagonists & inhibitors/genetics/*metabolism
MH  - Hydrogen Bonding
MH  - Kinetics
MH  - Models, Molecular
MH  - Peroxidases/antagonists & inhibitors/genetics/*metabolism
MH  - Polychaeta
MH  - Protein Conformation
MH  - Substrate Specificity
EDAT- 2013/08/21 06:00
MHDA- 2014/02/12 06:00
CRDT- 2013/08/20 06:00
PHST- 2013/08/20 06:00 [entrez]
PHST- 2013/08/21 06:00 [pubmed]
PHST- 2014/02/12 06:00 [medline]
AID - 10.1021/bi400627w [doi]
PST - ppublish
SO  - Biochemistry. 2013 Sep 10;52(36):6203-10. doi: 10.1021/bi400627w. Epub 2013 Aug 
      29.