| 1. |
- Edholm, Olle, et al.
(author)
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The effect of water on the Fe3+/Fe2+ reduction potential of heme
- 2000
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In: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 268:3, s. 683-687
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Journal article (peer-reviewed)abstract
- Hemeproteins can act as catalysts, oxygen carriers or electron conductors. The ferric/ferrous reduction potential E-m7 of iron in the center of the prosthetic group ranges from negative values for peroxidases to an extreme positive value for cytochrome a, with Hb and Mb in the middle [1]. Proteins exercise their influence on E-m7 in several ways: via substituents at the periphery of the chelate structure, via the proximal ligand, and via interaction with the surrounding medium, amino acid side chains, or polar solvents. Work on recombined proteins and ap-substituted free hemes documented that the first two effects are additive [2]. For the third effect, models of the dielectric media on a molecular level have been successfully applied [3-5]. E-m7 has also been empirically correlated to the degree of heme exposure to water [6-8]. The apoprotein/porphyrin and water/porphyrin interfaces are complementary since water molecules fill any empty space in the crevice and surround any pertinent part of heme outside the protein boundary. The present work links to this idea by a combination of statistical mechanics simulations and quantum mechanical calculations comparing heme in water with heme in an apolar environment. Our results show that polarization of the porphyrin pi-electron cloud by the held from water dipoles influences E-m7 The dominant effect of this and other determinates of iron electron availability is perturbations of delocalized electron density in the porphyrin chelate, reproduced by a model where the prosthetic group is treated as a disc of uniform electron density. The present work is also of interest since the interfacial energy constitutes the main barrier for heme-protein Separation [9-11].
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| 4. |
- Nordlander, Johan, et al.
(author)
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Reactive objects
- 2002
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In: Fifth IEEE International Symposium on Object-Oriented Real-Time Distributed Computing. - Piscataway, NJ : IEEE Communications Society. ; , s. 155-158
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Conference paper (peer-reviewed)abstract
- Object-oriented, concurrent, and event-based programming models provide a natural framework in which to express the behavior of distributed and embedded software systems. However, contemporary programming languages still base their I/O primitives on a model in which the environment is assumed to be centrally controlled and synchronous, and interactions with the environment carried out through blocking subroutine calls. The gap between this view and the natural asynchrony of the real world has made event-based programming a complex and error-prone activity, despite recent focus on event-based frameworks and middleware. In this paper we present a consistent model of event-based concurrency, centered around the notion of reactive objects. This model relieves the object-oriented paradigm from the idea of transparent blocking, and naturally enforces reactivity and state consistency. We illustrate our point by a program example that offers substantial improvements in size and simplicity over a corresponding Java-based solution.
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| 5. |
- Fontal-Cazalla, F.M., Buffington, M., Nordlander, G., Liljeblad, J., Ros-Farré, P., Nieves-Aldrey, J.L., Pujade-Villar, J. & Ronquist, F.
(author)
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Phylogeny of the Eucoilinae (Hymenoptera: Cynipoidea: Figitidae).
- 2002
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In: Cladistics. ; :18, s. 154-199
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Journal article (peer-reviewed)
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| 6. |
- Grachova, E V, et al.
(author)
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The structure and dynamic behaviour of disubstituted derivatives of Rh6(CO)16 containing heterobidentate bridging phosphine ligands
- 2003
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; :12, s. 2468-2473
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Journal article (peer-reviewed)abstract
- The solution structures and dynamic behaviour of [Rh6(CO)14(µ-PX)][PX = diphenyl(2-pyridyl)phosphine, (PN); diphenyl(2-thienyl)phosphine, (PS); diphenyl(vinyl)phosphine, (PV)] have been studied by multinuclear NMR and the X-ray structure of [Rh6(CO)14(µ,3-PV)] is reported. In solution, the above clusters undergo a variety of localised CO-exchanges and the mechanisms of these are discussed. The PV ligand in [Rh6(CO)14(µ,3-PV)] is hemilabile and exhibits facile exchange/reorientation of the vinyl group.
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| 7. |
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| 9. |
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| 10. |
- Tunik, S P, et al.
(author)
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Chiral hexarhodium clusters containing heterobidentate phosphine ligands, a structural and reactivity study
- 2003
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234. ; :12, s. 2457-2467
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Journal article (peer-reviewed)abstract
- Some intrinsically chiral [Rh6(CO)14(µ,2-PX)] clusters have been synthesized, beginning with reactions of [Rh6(CO)16–x(NCMe)x](x= 1, 2) with PX, where PX represents the bidentate bridging ligands diphenyl(benzothienyl)phosphine (1), diphenyl(2-thienyl)phosphine (2), di(2-thienyl)phenylphosphine (3), tris(2-thienyl)phosphine (4), diphenyl(2-pyridyl)phosphine (5) and diphenylvinylphosphine (6). The ligand tris(2-furyl)phosphine (7) shows no bridging capability. When x= 1 the initial products are the clusters [Rh6(CO)15(1-PX)] which undergo spontaneous CO loss to form [Rh6(CO)14(µ,2-PX)]. The structures of the [Rh6(CO)15(1-PX)] clusters have been elucidated by IR, NMR spectroscopy and FAB-MS spectrometry, and have been found to involve phosphorus atom coordination to a rhodium atom. In addition, the solid state structures of the [Rh6(CO)14(µ,2-Ph2P(2-benzothienyl))](8), [Rh6(CO)14(µ,2-Ph2P(2-thienyl))](9), [Rh6(CO)14(µ,2-PhP(2-thienyl)2)](10) and [Rh6(CO)14(µ,2-Ph2P(pyridyl))](12) clusters have been determined by X-ray crystallography. The various types of chirality exhibited by these clusters are discussed. A simple model is proposed to account for the ratios of stereochemical isomers found in the Rh6(CO)14(µ,2-PhP(2-thienyl)2 cluster. The kinetics of formation of the bridged clusters from the monosubstituted [Rh6(CO)15(1-PX)] clusters have been studied.
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| 11. |
- Tunik, S P, et al.
(author)
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Reactions of [H2OS3(CO)(10)] with conjugated diynes (RC2C2R ') containing nucleophilic oxygen in beta position of a substituent (R = Ph, R ' = CH2OH, C(O)Ph; R = R ' = CMe2(OH))
- 2003
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In: Organometallics. - : American Chemical Society (ACS). - 1520-6041 .- 0276-7333. ; 22:17, s. 3455-3465
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Journal article (peer-reviewed)abstract
- Reactions of [H2Os3(CO)10] with a series of diynes, RC2C2R' (1: R = Ph, R' = CH2OH; 2: R = Ph, R' = C(O)Ph; 3: R = R' = C(OH)Me2), have been studied. It was found that upon coordination to the triosmium cluster, the nucleophilic oxygens of the R' substituents of 1 and 2 take part in intramolecular cyclization reactions to give [HOs3(CO)10{-1:2-PhCH2(C=CH-C=CH-O)}] (5) and [HOs3(CO)10{-1:1-Ph(C=CH-C=C-O)CPh}] (6), respectively, both of which contain furan rings coordinated to the cluster core. On heating of the latter compound, the furan moiety remains intact, but a carbonyl group dissociates from the cluster, leading to the formation of [HOs3(CO)9(3-1:3:1-Ph(C=CH-C=C-O)CPh)] (7) with a closed "C3Os3" pentagonal pyramidal structure. Reaction of [H2Os3(CO)10] with 3 does not lead to cyclization of the diyne; instead, the clusters [Os3(CO)10{3-2-(RCH=CH-C2R)}] (8) and [Os3(CO)10{3-2-(RC2C2R)}] (9) are formed. Deuterium labeling of the starting compounds has been used in the reaction of [H2Os3(CO)10] with HOCH2C2C2CH2OH in order to investigate possible mechanisms of the cyclization reaction. The crystal and molecular structures of clusters 5, 7, and 9 are presented.
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