Synthesis and characterization of hydroxo-bridged diiron(III) complexes containing carboxylate or phosphate ester bridges: comparisons to diiron(III) proteins

Turowski, Petra N.; Armstrong, William H.; Liu, Shuncheng; Brown, Seth N.; Lippard, Stephen J.

doi:10.1021/ic00082a006

Cited by 79 publications

(66 citation statements)

References 4 publications

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“…We propose that the 2.11-Å shell consists of the three protein-derived ligands as well as a terminal solvent ligand, while the 1.95-Å shell can be reasonably assigned to hydroxo ligands. One of the latter scatterers very likely corresponds to the μ -OH bridge found in hDOHH- R , as analogous bridges in synthetic diferric complexes have Fe III -( μ -OH) distances between 1.94 Å and 2.02 Å [55, 60, 84–87]. The other scatterer could, in principle, be assigned to a second hydroxo bridge, but such an Fe III 2 ( μ -OH) 2 core should give rise to an Fe•••Fe distance much shorter than the 3.41-Å separation found for hDOHH- D and hDOHH- D•S .…”

Section: Discussionmentioning

confidence: 99%

X-ray absorption spectroscopic characterization of the diferric-peroxo intermediate of human deoxyhypusine hydroxylase in the presence of its substrate eIF5a

Jasniewski

Engstrom

et al. 2016

J Biol Inorg Chem

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Human deoxyhypusine hydroxylase (hDOHH) is an enzyme that is involved in the critical post-translational modification of the eukaryotic translation initiation factor 5A (eIF5A). Following the conversion of a lysine residue on eIF5A to deoxyhypusine (Dhp) by deoxyhypusine synthase, hDOHH hydroxylates Dhp to yield the unusual amino acid residue hypusine (Hpu), a modification that is essential for eIF5A to promote peptide synthesis at the ribosome, among other functions. Purification of hDOHH overexpressed in E. coli affords enzyme that is blue in color, a feature that has been associated with the presence of a peroxo-bridged diiron(III) active site. To gain further insight into the nature of the diiron site and how it may change as hDOHH goes through the catalytic cycle, we have conducted X-ray absorption spectroscopic studies of hDOHH on five samples that represent different species along its reaction pathway. Structural analysis of each species has been carried out, starting with the reduced diferrous state, proceeding through its O2 adduct, and ending with a diferric decay product. Our results show that the Fe•••Fe distances found for the five samples fall within a narrow range of 3.4–3.5 Å, suggesting that hDOHH has a fairly constrained active site. This pattern differs significantly from what has been associated with canonical dioxygen activating nonheme diiron enzymes such as soluble methane monooxygenase and Class 1A ribonucleotide reductases, for which the Fe•••Fe distance can change by as much as 1 Å during the redox cycle. These results suggest that the O2 activation mechanism for hDOHH deviates somewhat from that associated with the canonical nonheme diiron enzymes, opening the door to new mechanistic possibilities for this intriguing family of enzymes.

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Section: Discussionmentioning

confidence: 99%

X-ray absorption spectroscopic characterization of the diferric-peroxo intermediate of human deoxyhypusine hydroxylase in the presence of its substrate eIF5a

Jasniewski

Engstrom

et al. 2016

J Biol Inorg Chem

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“…28 Some additional dinuclear transition metal complexes of phosphate esters are listed in Table 6. [24][25][26][27][28][29][30][31][32][33] The Zn‚‚‚Co interatomic distance is 3.846(1) Å, which is longer by Scheme 2 a a L ) CH3OH. 0.406 Å than that found in the acac-bridged ZnCo complex 2 and by 0.151 Å than that of [Zn II Fe III (BPMP)(µ-η 2 -DPP) 2 ]-(ClO 4 ) 2 (3.695(1) Å).…”

Section: Reaction Of [Znm(xdk)(acac) 2 (Ch 3 Oh) 2 ]‚H 2 O (M ) Co 2+mentioning

confidence: 99%

Zinc-Containing Carboxylate-Bridged Heterodimetallic Complexes and Their Reactions with Phosphodiester Ligands

1996

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A series of zinc-containing heterodimetallic complexes were prepared by using the dinucleating ligand XDK [H 2 XDK ) m-xylylenediamine bis(Kemp's triacid imide)]. Mononuclear [Zn(XDK)(H 2 O)] (1) reacts with 1 equiv of M(acac) 2 ‚2H 2 O (acac ) 2,4-pentanedionate) to afford the heterodimetallic compounds [Zn II M II (XDK)(acac) 2 (CH 3 OH) 2 ]‚H 2 O (2‚H 2 O, M ) Co, 65% isolated yield; 3‚H 2 O, M ) Mn, 54%; 4‚H 2 O, M ) Fe, 30%; 5‚H 2 O, M ) Ni, 32%). As determined by X-ray crystallography, 2-5 each contain a Zn II M II dinuclear core bridged by XDK and acac ligands. The zinc and M atoms have trigonal bipyramidal and octahedral geometries, respectively. The Zn‚‚‚M separations depend on the metal ion in the octahedral site (2, M ) Co, 3.440(2) Å; 3, M ) Mn, 3.517(1) Å; 4, M ) Fe, 3.492(1) Å; 5, M ) Ni, 3.397(1) Å), a variation which is correlated with the ionic radius of the high-spin octahedral metal ion. The reaction of 2 with diphenyl hydrogen phosphate afforded the bis(phosphate) complex [ZnCo(XDK){µ-η 2 -(PhO) 2 PO 2 }{η 1 -(PhO) 2 PO 2 }(CH 3 OH) 2 (H 2 O)] (7, 49% yield). The ZnCo center is bridged by the XDK through its two carboxylate groups and by a diphenyl phosphate ligand. The other diphenyl phosphate is terminally coordinated to the zinc atom in a monodentate fashion. The Zn‚‚‚Co interatomic distance is 3.846 (1) Å. An analogous bis(phosphate) homodinuclear complex, [Zn 2 (XDK){µ-η 2 -(PhO) 2 PO 2 }{η 1 -(PhO) 2 PO 2 }(CH 3 OH) 2 (H 2 O)] (8), was prepared by reacting [Zn 2 (XDK)(acac) 2 (CH 3 OH) 2 ] (6) with diphenyl hydrogen phosphate in 64% yield. Compound 8, which is isomorphous with 7, has an asymmetrical dizinc core bridged by XDK and a phosphate ligand (Zn‚‚‚Zn ) 3.869(2) Å). The monodentate diphenyl phosphate ligand dissociates from the dimetallic center of 8 in solution, as revealed by molar conductivity and 1 H and 31 P{ 1 H} NMR spectroscopic studies. The resulting free phosphate ligand exchanges with the bridging one in methanol-d 4 . The present results provide a useful synthetic route to carboxylate-bridged heterodimetallic compounds, which are potential models for the active centers in nonredox metalloproteins. Crystal data are as follows. 2: monoclinic, P2 1 /c, a ) 17.725 (7) Å, b ) 12.354(4) Å, c ) 21.815(6) Å, ) 90.45(3)°, V ) 4777(2) Å 3 , Z ) 4; R ) 0.049 and R w ) 0.051 for 3884 reflections with I > 3σ(I). 3: monoclinic, P2 1 /c, a ) 17.292(2) Å, b ) 12.450(1) Å, c ) 21.717(2) Å, ) 91.464(7)°, V ) 4673.9(7) Å 3 , Z ) 4; R ) 0.046 and R w ) 0.051 for 3876 reflections. 4: monoclinic, P2 1 /c, a ) 17.630(1) Å, b ) 12.374(2) Å, c ) 21.771(2) Å, ) 90.306(8)°, V ) 4749.4(7) Å 3 , Z ) 4; R ) 0.041 and R w ) 0.049 for 3248 reflections. 5: monoclinic, P2 1 /c, a ) 17.817(2) Å, b ) 12.241(3) Å, c ) 21.786(2) Å, ) 91.043(9)°, V ) 4751(1) Å 3 , Z ) 4; R ) 0.050 and R w ) 0.058 for 4497 reflections. 7‚CH 3 OH: monoclinic, P2 1 /n, a ) 18.812(2) Å, b ) 16.156(2) Å, c ) 21.760(2) Å, ) 112.836(9)°, V ) 6095(1) Å 3 , Z ) 4; R ) 0.055 and R w ) 0.064 for 5843 reflections. 8‚CH 3 OH: monoclinic,...

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“…Methane monooxygenase also differs from the R2 protein of ribonucleotide reductase by having a hydroxo species as the bridging oxygen instead of a ,u-0x0 group. The absorbance in the 300-400 nm region of ribonucleotide reductase has been assigned to an 0x0 -+ Fe3' charge transfer band [27] which is shifted to lower wavelengths when the oxygen is protonated [28], accounting for the lack of electronic absorption above 300 nm in methane monooxygenase. An additional feature of both the methane monooxygenase and ribonucleotide reductase active sites is the presence of a hydrophobic cavity formed adjacent to the iron center by a series of conserved residues within the four-helical bundle (Fig.…”

Section: Introductionmentioning

confidence: 99%

The active site of the cyanide‐resistant oxidase from plant mitochondria contains a binuclear iron center

1995

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The cyanide-resistant, alternative oxidase of plant mitochondria catalyzes the four-electron reduction of oxygen to water, but the nature of the catalytic center associated with this oxidase has yet to be elucidated. We have identified conserved amino acids, including two copies of the iron-binding motif GIu-X-X-His, in the carboxy-terminal hydrophilic domain of the alternative oxidase that suggest the presence of a hydroxo-bridged binuclear iron center, analogous to that found in the enzyme methane monooxygenase. Using the known three-dimensional structures of other binuclear iron proteins, we have developed a structural model for the proposed catalytic site of the alternative oxidase based on these amino acid sequence similarities.

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Synthesis and characterization of hydroxo-bridged diiron(III) complexes containing carboxylate or phosphate ester bridges: comparisons to diiron(III) proteins

Cited by 79 publications

References 4 publications

X-ray absorption spectroscopic characterization of the diferric-peroxo intermediate of human deoxyhypusine hydroxylase in the presence of its substrate eIF5a

X-ray absorption spectroscopic characterization of the diferric-peroxo intermediate of human deoxyhypusine hydroxylase in the presence of its substrate eIF5a

Zinc-Containing Carboxylate-Bridged Heterodimetallic Complexes and Their Reactions with Phosphodiester Ligands

The active site of the cyanide‐resistant oxidase from plant mitochondria contains a binuclear iron center

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