1fz2: Difference between revisions

Revision as of 13:44, 21 February 2008

METHANE MONOOXYGENASE HYDROXYLASE, FORM II MIXED-VALENT GENERATED BY CRYSTAL SOAKING

OverviewOverview

The oxidation of methane to methanol is performed at carboxylate-bridged dinuclear iron centers in the soluble methane monooxygenase hydroxylase (MMOH). Previous structural studies of MMOH, and the related R2 subunit of ribonucleotide reductase, have demonstrated the occurrence of carboxylate shifts involving glutamate residues that ligate the catalytic iron atoms. These shifts are thought to have important mechanistic implications. Recent kinetic and theoretical studies have also emphasized the importance of hydrogen bonding and pH effects at the active site. We report here crystal structures of MMOH from Methylococcus capsulatus (Bath) in the diiron(II), diiron(III), and mixed-valent Fe(II)Fe(III) oxidation states, and at pH values of 6.2, 7.0, and 8.5. These structures were investigated in an effort to delineate the range of possible motions at the MMOH active site and to identify hydrogen-bonding interactions that may be important in understanding catalysis by the enzyme. Our results present the first view of the diiron center in the mixed-valent state, and they indicate an increased lability for ferrous ions in the enzyme. Alternate conformations of Asn214 near the active site according to redox state and a distortion in one of the alpha-helices adjacent to the metal center in the diiron(II) state have also been identified. These changes alter the surface of the protein in the vicinity of the catalytic core and may have implications for small-molecule accessibility to the active site and for protein component interactions in the methane monooxygenase system. Collectively, these results help to explain previous spectroscopic observations and provide new insight into catalysis by the enzyme.

About this StructureAbout this Structure

1FZ2 is a Protein complex structure of sequences from Methylococcus capsulatus with and as ligands. Active as Methane monooxygenase, with EC number 1.14.13.25 Full crystallographic information is available from OCA.

ReferenceReference

Crystal structures of the soluble methane monooxygenase hydroxylase from Methylococcus capsulatus (Bath) demonstrating geometrical variability at the dinuclear iron active site., Whittington DA, Lippard SJ, J Am Chem Soc. 2001 Feb 7;123(5):827-38. PMID:11456616

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-[[Image:1fz2.gif|left|200px]]<br /><applet load="1fz2" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1fz2.gif|left|200px]]<br /><applet load="1fz2" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1fz2, resolution 2.15&Aring;" />
 '''METHANE MONOOXYGENASE HYDROXYLASE, FORM II MIXED-VALENT GENERATED BY CRYSTAL SOAKING'''<br />
 ==Overview==
-The oxidation of methane to methanol is performed at carboxylate-bridged, dinuclear iron centers in the soluble methane monooxygenase hydroxylase, (MMOH). Previous structural studies of MMOH, and the related R2 subunit of, ribonucleotide reductase, have demonstrated the occurrence of carboxylate, shifts involving glutamate residues that ligate the catalytic iron atoms., These shifts are thought to have important mechanistic implications., Recent kinetic and theoretical studies have also emphasized the importance, of hydrogen bonding and pH effects at the active site. We report here, crystal structures of MMOH from Methylococcus capsulatus (Bath) in the, diiron(II), diiron(III), and mixed-valent Fe(II)Fe(III) oxidation states, and at pH values of 6.2, 7.0, and 8.5. These structures were investigated, in an effort to delineate the range of possible motions at the MMOH active, site and to identify hydrogen-bonding interactions that may be important, in understanding catalysis by the enzyme. Our results present the first, view of the diiron center in the mixed-valent state, and they indicate an, increased lability for ferrous ions in the enzyme. Alternate conformations, of Asn214 near the active site according to redox state and a distortion, in one of the alpha-helices adjacent to the metal center in the diiron(II), state have also been identified. These changes alter the surface of the, protein in the vicinity of the catalytic core and may have implications, for small-molecule accessibility to the active site and for protein, component interactions in the methane monooxygenase system. Collectively, these results help to explain previous spectroscopic observations and, provide new insight into catalysis by the enzyme.
+The oxidation of methane to methanol is performed at carboxylate-bridged dinuclear iron centers in the soluble methane monooxygenase hydroxylase (MMOH). Previous structural studies of MMOH, and the related R2 subunit of ribonucleotide reductase, have demonstrated the occurrence of carboxylate shifts involving glutamate residues that ligate the catalytic iron atoms. These shifts are thought to have important mechanistic implications. Recent kinetic and theoretical studies have also emphasized the importance of hydrogen bonding and pH effects at the active site. We report here crystal structures of MMOH from Methylococcus capsulatus (Bath) in the diiron(II), diiron(III), and mixed-valent Fe(II)Fe(III) oxidation states, and at pH values of 6.2, 7.0, and 8.5. These structures were investigated in an effort to delineate the range of possible motions at the MMOH active site and to identify hydrogen-bonding interactions that may be important in understanding catalysis by the enzyme. Our results present the first view of the diiron center in the mixed-valent state, and they indicate an increased lability for ferrous ions in the enzyme. Alternate conformations of Asn214 near the active site according to redox state and a distortion in one of the alpha-helices adjacent to the metal center in the diiron(II) state have also been identified. These changes alter the surface of the protein in the vicinity of the catalytic core and may have implications for small-molecule accessibility to the active site and for protein component interactions in the methane monooxygenase system. Collectively, these results help to explain previous spectroscopic observations and provide new insight into catalysis by the enzyme.
 ==About this Structure==
-FZ2 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Methylococcus_capsulatus Methylococcus capsulatus] with FE2 and CA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Methane_monooxygenase Methane monooxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.13.25 1.14.13.25] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1FZ2 OCA].
+FZ2 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Methylococcus_capsulatus Methylococcus capsulatus] with <scene name='pdbligand=FE2:'>FE2</scene> and <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Methane_monooxygenase Methane monooxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.13.25 1.14.13.25] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FZ2 OCA].
 ==Reference==
@@ Line 14: / Line 14: @@
 [[Category: Methylococcus capsulatus]]
 [[Category: Protein complex]]
-[[Category: Lippard, S.J.]]
+[[Category: Lippard, S J.]]
-[[Category: Whittington, D.A.]]
+[[Category: Whittington, D A.]]
 [[Category: CA]]
 [[Category: FE2]]
@@ Line 21: / Line 21: @@
 [[Category: monooxygenase]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 15:29:40 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:44:11 2008''