Exploring Spirituality in Teaching Within a Christian School Context Through Collaborative Action Research

This article reports on a collaborative action research project conducted in New Zealand, during 2012, exploring spirituality in teaching within a Christian school context. The experienced primary school teacher participant chose to take action around the issue of personal fear and insecurity which were believed to be hindering professional growth and relationships. Through self-directed inquiry, critical reflective journaling, Bible study, fellowship and prayer with trusted friends, the teacher experienced a renewed sense of peace and freedom in Christ. This personal transformation was believed to be influential on subsequent professional practice, assisting the teacher to become more relational, responsive and compassionate. The findings provide a rich description of the participant’s spirituality, the lived reality of a person’s spiritual life. This report will be of interest to teachers, teacher-leaders and teacher-educators who desire to explore Christian spirituality through practitioner-led inquiry

Spectroscopic Studies of the Iron and Manganese Reconstituted Tyrosyl Radical in Bacillus Cereus Ribonucleotide Reductase R2 Protein

Ribonucleotide reductase (RNR) catalyzes the rate limiting step in DNA synthesis where ribonucleotides are reduced to the corresponding deoxyribonucleotides. Class Ib RNRs consist of two homodimeric subunits: R1E, which houses the active site; and R2F, which contains a metallo cofactor and a tyrosyl radical that initiates the ribonucleotide reduction reaction. We studied the R2F subunit of B. cereus reconstituted with iron or alternatively with manganese ions, then subsequently reacted with molecular oxygen to generate two tyrosyl-radicals. The two similar X-band EPR spectra did not change significantly over 4 to 50 K. From the 285 GHz EPR spectrum of the iron form, a g1-value of 2.0090 for the tyrosyl radical was extracted. This g1-value is similar to that observed in class Ia E. coli R2 and class Ib R2Fs with iron-oxygen cluster, suggesting the absence of hydrogen bond to the phenoxyl group. This was confirmed by resonance Raman spectroscopy, where the stretching vibration associated to the radical (C-O, ν7a = 1500 cm−1) was found to be insensitive to deuterium-oxide exchange. Additionally, the 18O-sensitive Fe-O-Fe symmetric stretching (483 cm−1) of the metallo-cofactor was also insensitive to deuterium-oxide exchange indicating no hydrogen bonding to the di-iron-oxygen cluster, and thus, different from mouse R2 with a hydrogen bonded cluster. The HF-EPR spectrum of the manganese reconstituted RNR R2F gave a g1-value of ∼2.0094. The tyrosyl radical microwave power saturation behavior of the iron-oxygen cluster form was as observed in class Ia R2, with diamagnetic di-ferric cluster ground state, while the properties of the manganese reconstituted form indicated a magnetic ground state of the manganese-cluster. The recent activity measurements (Crona et al., (2011) J Biol Chem 286: 33053–33060) indicates that both the manganese and iron reconstituted RNR R2F could be functional. The manganese form might be very important, as it has 8 times higher activity

Alzheimer's Aβ Peptides with Disease-Associated N-Terminal Modifications: Influence of Isomerisation, Truncation and Mutation on Cu2+ Coordination

coordination of various Aβ peptides has been widely studied. A number of disease-associated modifications involving the first 3 residues are known, including isomerisation, mutation, truncation and cyclisation, but are yet to be characterised in detail. In particular, Aβ in plaques contain a significant amount of truncated pyroglutamate species, which appear to correlate with disease progression. coordination modes between pH 6–9 with nominally the same first coordination sphere, but with a dramatically different pH dependence arising from differences in H-bonding interactions at the N-terminus. coordination of Aβ, which may be critical for alterations in aggregation propensity, redox-activity, resistance to degradation and the generation of the Aβ3–× (× = 40/42) precursor of disease-associated Aβ3[pE]–x species

Complexation du cuivre par les peptides impliqués dans les maladies neurodégénératives

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Interaction of YZ with its environment in acetate treated photosystem II membranes and reaction center cores

The photosynthetic oxidation of water to oxygen occurs in photosystem II (PSII) at an active site composed of a tetranuclear cluster of manganese ions, a redox active tyrosine, YZ, and two essential cofactors, calcium and chloride. Recently, several experimental observations have led to the proposal of a metalloradical catalytic cycle in which water oxidation occurs via hydrogen-atom abstraction by the tyrosyl radical from water bound to the manganese cluster. This model predicts a close proximity between the radical tyrosine, Yz\u2022, and the Mn cluster and the involvement of the radical in a bifurcated hydrogen bond. Magnetic resonance techniques have been used in this work to probe the interaction of the tyrosyl radical with its environment in PSII samples in which the catalytic cycle is blocked by acetate treatment and the enzyme is trapped in a paramagnetic S2Yz\u2022 state. Radical interaction with the metal cluster has been studied via simulations of the EPR spectra obtained for this state. The simulations were based on a radical-pair model and included terms for both electron 12electron dipolar and exchange interactions. The results show a dominant exchange interaction between the radical and the manganese cluster in these preparations and led to an estimate of 8 129 \uc5 for the spin 12spin distance. ESEEM spectroscopy and 1H2O/2H2O exchange were used to study interactions of the S2Yz\u2022 state with exchangeable hydrogen nuclei in the site. Two-pulse ESEEM data show features expected for a radical-pair species, in support of our analysis of the continuous-wave EPR spectrum. An ESEEM analysis based on an electron spin 1/2, nuclear spin 1 model shows that both two- and three-pulse ESEEM data are consistent with four deuterons that exhibit an electron 12nuclear dipole 12dipole coupling of 0.42 MHz. The validity of this analysis and its implications for the oxygen-evolving apparatus are discussed

Iron-catalyzed C―C cross-coupling in the absence of additional ligands: active species and off-cycle pathways

International audienceIron-catalyzed cross-coupling between a Grignard reagent RMgX and an electrophile R'─X was discovered by Kochi in the 1970s and witnessed recent improvements. This transformation can be carried out using simple iron salts such as FeCl$_2$ , FeCl$_3$ or Fe(acac)$_3$ in the absence of additional ligand. However, these systems lead to short-lived reactive species, making in-situ mechanistic analysis challenging. By means of Mössbauer, cw-and pulse-EPR spectroscopies, we demonstrated that two arene-stabilized Fe$^0$ and Fe$^I$ resting states were obtained by reduction of the precursor in toluene (Fig. 1a). Analysis of the bulk revealed that the ($\eta^4$-C$_6$H$_5$Me)$_2$Fe$^0$ complex catalyzes efficiently aryl-heteroaryl coupling, via a Fe$^0$ /Fe$^{II}$ cycle (Fig. 1b). Preliminary results moreover show that transient tris(aryl) species such as [Ph$_3$ Fe$^{II}$ ]-are key intermediates in the formation of the lower oxidation states. Fe$^0$ and Fe$^I$ are respectively afforded by 2-electron reductive elimination and by redox disproportionation of the +II ox. state

Iron-catalyzed C―C cross-coupling in the absence of additional ligands: active species and off-cycle pathways

International audienceIron-catalyzed cross-coupling between a Grignard reagent RMgX and an electrophile R'─X was discovered by Kochi in the 1970s and witnessed recent improvements. This transformation can be carried out using simple iron salts such as FeCl$_2$ , FeCl$_3$ or Fe(acac)$_3$ in the absence of additional ligand. However, these systems lead to short-lived reactive species, making in-situ mechanistic analysis challenging. By means of Mössbauer, cw-and pulse-EPR spectroscopies, we demonstrated that two arene-stabilized Fe$^0$ and Fe$^I$ resting states were obtained by reduction of the precursor in toluene (Fig. 1a). Analysis of the bulk revealed that the ($\eta^4$-C$_6$H$_5$Me)$_2$Fe$^0$ complex catalyzes efficiently aryl-heteroaryl coupling, via a Fe$^0$ /Fe$^{II}$ cycle (Fig. 1b). Preliminary results moreover show that transient tris(aryl) species such as [Ph$_3$ Fe$^{II}$ ]-are key intermediates in the formation of the lower oxidation states. Fe$^0$ and Fe$^I$ are respectively afforded by 2-electron reductive elimination and by redox disproportionation of the +II ox. state

SUGARS TO CONTROL LIGAND SHAPE IN METAL COMPLEXES : CONFORMATIONALLY CONSTRAINED GLYCOLIGANDS WITH A PREDETERMINATION OF STEREOCHEMISTRY AND A STRUCTURAL CONTROL

International audienceIn coordination chemistry, ligand shape can be used to tune properties, such as metal selectivity, coordination number, electronic structure, redox potential, and metal center stereochemistry including coordination helicates formation, and also to generate cavities for encapsulation. The results presented in this article indicate that two epimeric glycoligands (3 and 4) based on the conformationally restrained xylo- and ribo-1,2-O-isopropylidenefurano scaffolds are preorganized in water through pi-pi stacking due to hydrophobic interactions, as evidenced from excimer observation. The structure obtained in the solid state for one of the Cu(II) complexes (5) is chiral, with an original helical chirality arising from the coiling of the two ligands around the Cu-Cu axis. It shows an unusual double-deck type structure, with pi-pi interaction between two triazoyl-pyridyl rings and with a small cavity between the two Cu(II) ions able to host a bridging water molecule, as suggested by electron paramagnetic resonance. The Cu(II) complex from the epimeric ligand (6) shows similar properties with a mirror-image CD spectrum in the d-d region of the Cu(II). There is a predetermination of chirality at the metal center by the glycoligand induced by the C3 configuration, 6 and 5 being pseudoenantiomers. Interestingly, the stereochemistry at the metal center is here controlled by the combination of pi-stacking and chiral backbone