PMID- 10194372
OWN - NLM
STAT- MEDLINE
DCOM- 19990429
LR  - 20131121
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 38
IP  - 14
DP  - 1999 Apr 6
TI  - Reactions of nitric oxide with the reduced non-heme diiron center of the soluble 
      methane monooxygenase hydroxylase.
PG  - 4504-13
AB  - The soluble methane monooxygenase system from Methylococcus capsulatus (Bath) 
      catalyzes the oxidation of methane to methanol and water utilizing dioxygen at a 
      non-heme, carboxylate-bridged diiron center housed in the hydroxylase (H) 
      component. To probe the nature of the reductive activation of dioxygen in this 
      system, reactions of an analogous molecule, nitric oxide, with the diiron(II) 
      form of the enzyme (Hred) were investigated by both continuous and discontinuous 
      kinetics methodologies using optical, EPR, and Mossbauer spectroscopy. Reaction 
      of NO with Hred affords a dinitrosyl species, designated Hdinitrosyl, with 
      optical spectra (lambdamax = 450 and 620 nm) and Mossbauer parameters (delta = 
      0.72 mm/s, DeltaEQ = 1.55 mm/s) similar to those of synthetic dinitrosyl 
      analogues and of the dinitrosyl adduct of the reduced ribonucleotide reductase R2 
      (RNR-R2) protein. The Hdinitrosyl species models features of the Hperoxo 
      intermediate formed in the analogous dioxygen reaction. In the presence of 
      protein B, Hdinitrosyl builds up with approximately the same rate constant as 
      Hperoxo ( approximately 26 s-1) at 4 degrees C. In the absence of protein B, the 
      kinetics of Hdinitrosyl formation were best fit with a biphasic A --> B --> C 
      model, indicating the presence of an intermediate species between Hred and 
      Hdinitrosyl. This result contrasts with the reaction of Hred with dioxygen, in 
      which the Hperoxo intermediate forms in measurable quantities only in the 
      presence of protein B. These findings suggest that protein B may alter the 
      positioning but not the availability of coordination sites on iron for exogenous 
      ligand binding and reactivity.
FAU - Coufal, D E
AU  - Coufal DE
AD  - Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139, 
      USA.
FAU - Tavares, P
AU  - Tavares P
FAU - Pereira, A S
AU  - Pereira AS
FAU - Hyunh, B H
AU  - Hyunh BH
FAU - Lippard, S J
AU  - Lippard SJ
LA  - eng
GR  - GM32134/GM/NIGMS NIH HHS/United States
GR  - GM47295/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Bacterial Proteins)
RN  - 0 (CAMP protein, Streptococcus)
RN  - 0 (Ferrous Compounds)
RN  - 0 (Hemolysin Proteins)
RN  - 0 (Nonheme Iron Proteins)
RN  - 31C4KY9ESH (Nitric Oxide)
RN  - EC 1.13.- (Oxygenases)
RN  - EC 1.14.13.25 (methane monooxygenase)
RN  - EC 1.17.4.- (Ribonucleotide Reductases)
RN  - EC 1.17.4.- (ribonucleotide reductase R2 subunit)
SB  - IM
MH  - Bacterial Proteins/chemistry
MH  - Electron Spin Resonance Spectroscopy
MH  - Ferrous Compounds/chemical synthesis/*chemistry
MH  - Hemolysin Proteins
MH  - Methylococcaceae/*enzymology
MH  - Models, Molecular
MH  - Nitric Oxide/*chemistry
MH  - Nonheme Iron Proteins/chemical synthesis/chemistry
MH  - Oxidation-Reduction
MH  - Oxygenases/chemical synthesis/*chemistry
MH  - Ribonucleotide Reductases/chemistry
MH  - Solubility
MH  - Spectrophotometry
MH  - Spectroscopy, Mossbauer
EDAT- 1999/04/09 00:00
MHDA- 1999/04/09 00:01
CRDT- 1999/04/09 00:00
PHST- 1999/04/09 00:00 [pubmed]
PHST- 1999/04/09 00:01 [medline]
PHST- 1999/04/09 00:00 [entrez]
AID - bi9823378 [pii]
AID - 10.1021/bi9823378 [doi]
PST - ppublish
SO  - Biochemistry. 1999 Apr 6;38(14):4504-13. doi: 10.1021/bi9823378.