Molecular species containing persistent voids. Template synthesis and characterization of a series of lacunar-nickel(II) complexes and the corresponding free ligands

Busch, Daryle H.; Olszanski, Dennis J.; Stevens, James C.; Schammel, Wayne P.; Kojima, Masayasu; Herron, Norman; Zimmer, L. Lawrence; Holter, Katherine A.; Mocák, Ján

doi:10.1021/ja00396a030

Cited by 30 publications

(13 citation statements)

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“…Earlier studies have documented the fact that electronic effects do not accompany the changes in the bridge structure (22,24).…”

Section: Resultsmentioning

confidence: 99%

“…Solvents were invariably distilled prior to use, using standard procedures. Syntheses of ligands as their nickel complexes with subsequent removal ofthe metal ion have been reported (22). All iron complexes were prepared under an atmosphere ofdry nitrogen, using a Vacuum Atmospheres (Hawthorne, CA) glove box (see below).…”

Section: Methodsmentioning

confidence: 99%

“…This is shown by direct equilibrium measurements with a family ofnonporphyrin heme protein models coupled with key crystal structure analyses. The ligands in our models contain superstructure components that facilitate control of the space available for the binding of CO to an iron(II) atom (22). These socalled lacunar ligands are neutral, bicyclic molecules having conformations that incorporate permanent voids in the vicinity of a metal coordination site (see Fig.…”

Section: Structural Analyses Of Carbonyl Hemoglobins and Carbonyl Myomentioning

confidence: 99%

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Steric control of CO binding in a totally synthetic heme protein model

Busch

Zimmer

Grzybowski

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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A family oftotally synthetic models for the carbon Rt monoxide adducts of heme proteins has been synthesized and ap-R2/ plied to the elucidation of the role of steric (13,14). It has been proposed that the crowding is responsible for the partial detoxification ofcarbon monoxide in respiring organisms (4, 11). For example, the ratio of equilibrium constants (12-18) for CO and 02 binding (formation) Kco/Ko2 for a protein-free modified heme having no structural counterpart to the distal imidazole (Traylor's chelated protoheme) is 840, whereas the corresponding ratio in myoglobin under comparable conditions is 20 (15). The discrimination against carbon monoxide by myoglobin is evident from the fact that the equilibrium constant for 02 binding for the chelated protoheme (2.0 x 106 M-1) is very close to the value for myoglobin (1.5 x 106 M-1). The behavior ofa model having an anthracene suspended above a porphyrin has given support to the conclusion that steric effects can weaken CO binding to heme iron (13). Studies on the equilibrium constants for CO and NO binding, both to model compounds and to heme proteins, confirm the role of a steric effect in weakening the binding of CO to myoglobin (19). In contrast, there is no substantial selective process, steric or otherwise, operating against the binding to iron of CO, as compared to 02, in the case of Hb(R) (12). These results generate two related questions, because the FeCO linkage is distorted (1-3) in both crystalline Hb(R)(CO) and crystalline Mb(CO): (i) Do steric effects that push the normally linear FeCO group into some off-axis configuration necessarily decrease the CO affinities of iron(II) complexes? (ii) If yes, are there structural differences between the carbon monoxide complex of Hb(R)(CO) in aqueous solutions or suspension (20) and in its crystalline state that would account for the apparent contradiction?The structural origins of modifications in 02 affinity are well illustrated by the T and R forms ofhemoglobin. For 02 binding, the equilibrium constant is altered by changes in the rate of dissociation and is attributable to constraints placed on the proximal imidazole by protein conformation and the ease with which the iron atom may occupy the N4 plane of the protoporphyrin (4-11, 21).We report here a systematic and definitive demonstration that steric effects can indeed control the CO affinity of iron(II). This is shown by direct equilibrium measurements with a family ofnonporphyrin heme protein models coupled with key crystal structure analyses. The ligands in our models contain superstructure components that facilitate control of the space available for the binding of CO to an iron(II) atom (22). These socalled lacunar ligands are neutral, bicyclic molecules having conformations that incorporate permanent voids in the vicinity of a metal coordination site (see Fig. 1). The efficacy of these synthetic species as biological mimics has been shown through studies on the reversibly formed 1:1 oxygen adducts of the cobalt(II) and iron(II) compl...

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“…Earlier studies have documented the fact that electronic effects do not accompany the changes in the bridge structure (22,24).…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Structural Analyses Of Carbonyl Hemoglobins and Carbonyl Myomentioning

confidence: 99%

See 1 more Smart Citation

Steric control of CO binding in a totally synthetic heme protein model

Busch

Zimmer

Grzybowski

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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“…Williamson etherifications, through the in situ formed (NaH) sodium alkoxide of 21, were initially attempted in DMF using the required diiodo-or dibromo-alkanes, but with poor results. Replacing halo-electrophiles with the more reactive ditosylates 26 35 and 27 36 and applying a protocol 37 which involved KOH as base and a more polar solvent (DMSO) furnished the desired dimers (25a,b) in a clean way and in good yields. 38 With the key intermediate dimers in our hands, we proceeded to the next steps, which involved installation of the butyryl and phosphate groups.…”

Section: Chemistrymentioning

confidence: 99%

Synthesis of inositol phosphate-based competitive antagonists of inositol 1,4,5-trisphosphate receptors

et al. 2016

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Inositol 1,4,5-trisphosphate receptors (IP3Rs) are intracellular Ca(2+) channels that are widely expressed in animal cells, where they mediate the release of Ca(2+) from intracellular stores evoked by extracellular stimuli. A diverse array of synthetic agonists of IP3Rs has defined structure-activity relationships, but existing antagonists have severe limitations. We combined analyses of Ca(2+) release with equilibrium competition binding to IP3R to show that (1,3,4,6)IP4 is a full agonist of IP3R1 with lower affinity than (1,4,5)IP3. Systematic manipulation of this meso-compound via a versatile synthetic scheme provided a family of dimeric analogs of 2-O-butyryl-(1,3,4,6)IP4 and (1,3,4,5,6)IP5 that compete with (1,4,5)IP3 for binding to IP3R without evoking Ca(2+) release. These novel analogs are the first inositol phosphate-based competitive antagonists of IP3Rs with affinities comparable to that of the only commonly used competitive antagonist, heparin, the utility of which is limited by off-target effects.

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“…[12,13] On the other hand, [14]cyclidenes are planar and very long bridges are necessary to close the second ring. [14] Similar reaction of the unsubstituted [14]cyclidene copper(II) or nickel(II) complexes with shorter di-A C H T U N G T R E N N U N G amines [(CH 2 ) [3][4][5][6][7][8][9] ], results in the formation of bridged bismacrocyclic complexes with tunable properties. [15,16] Here we describe synthesis and characterization of new polycyclic complexes with increasing number of tetraaza-…”

Section: Introductionmentioning

confidence: 99%

Macrocyclic Multicenter Complexes of Nickel and Copper of Increasing Complexity

Małecka

Lewandowska

Kamiński

et al. 2011

Chemistry A European J

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Multicenter (bi-, tri-, and tetranuclear) tetraazamacrocyclic complexes were self-assembled from Ni and Cu tetraazamacrocyclic mononuclear units and α,ω-diamines as building blocks. The structures of all compounds studied were proved by spectroscopic methods (ESI MS and NMR spectroscopy). Electrochemical experiments revealed reversible one-electron electrode processes at each of the Ni(2+) and Cu(2+) centers with formation of metal cations in oxidation state +3. Long linkers allow bi- and trinuclear complexes with noninteracting metal centers to be obtained. In the case of the short linkers (e.g. ethylenediamine) higher, trinuclear species are formed as major product. The structures of the bis- and tris-macrocyclic systems were confirmed by single-crystal X-ray diffraction. The tris-macrocyclic systems form cations in the shape of triangles partially filled with counterions and solvent molecules. The cations form positively charged layers, which interact in the crystal lattice with the neighboring negatively charged layers of anions. In solution, the trinuclear complexes exhibit strong host-guest interactions with 9,10-dimethyltriptycene due to complementarity of shape and size of this guest molecule. The association constants were determined by NMR spectroscopy and voltammetry, and very good agreement was obtained. The structural flexibility of the tetranuclear complex with long linkers allows for attractive interactions between the metal-complexing macrocycles that result in folding of the molecule. On the contrary, no folding is possible in the case of short linkers consisting of two CH(2) groups.

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Molecular species containing persistent voids. Template synthesis and characterization of a series of lacunar-nickel(II) complexes and the corresponding free ligands

Cited by 30 publications

References 0 publications

Steric control of CO binding in a totally synthetic heme protein model

Steric control of CO binding in a totally synthetic heme protein model

Synthesis of inositol phosphate-based competitive antagonists of inositol 1,4,5-trisphosphate receptors

Macrocyclic Multicenter Complexes of Nickel and Copper of Increasing Complexity

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