Regulation of Na+/K+ ATPase Transport Velocity by RNA Editing

Editing of Na+/K+ ATPase mRNAs modulates the Na+/K+ pump's turnover rate by selectively targeting the release of the final sodium to the outside

Hydroxylation of phenolic compounds by a peroxodicopper(II) complex: Further insight into the mechanism of tyrosinase

The dicopper(I) complex [Cu2(MeL66)]2+ (where MeL66 is the hexadentate ligand 3,5-bis-{bis-[2-(1-methyl-1H-benzimidazol-2-yl)-ethyl]-amino}-methylbenzene) reacts reversibly with dioxygen at low temperature to form a -peroxo adduct. Kinetic studies of O2 binding carried out in acetone in the temperature range from -80 to -55 °C yielded the activation parameters H1 = 40.4 ± 2.2 kJ mol-1, S1 = -41.4 ± 10.8 J K-1 mol-1 and H-1 = 72.5 ± 2.4 kJ mol-1, S-1 = 46.7 ± 11.1 J K-1 mol-1 for the forward and reverse reaction, respectively, and the binding parameters of O2 H° = -32.2 ± 2.2 kJ mol-1 and S° = -88.1 ± 10.7 J K-1 mol-1. The hydroxylation of a series of p-substituted phenolate salts by [Cu2(MeL66)O2]2+ studied in acetone at -55 °C indicates that the reaction occurs with an electrophilic aromatic substitution mechanism, with a Hammett constant =-1.84. The temperature dependence of the phenol hydroxylation was studied between -84 and -70 °C for a range of sodium p-cyanophenolate concentrations. The rate plots were hyperbolic and enabled to derive the activation parameters for the monophenolase reaction Hox = 29.1  3.0 kJ mol-1, Sox = -115  15 J K-1 mol-1 and the binding parameters of the phenolate to the -peroxo species H°b = -8.1  1.2 kJ mol-1 and S°b = -8.9  6.2 J K-1 mol-1. Thus, the complete set of kinetic and thermodynamic parameters for the two separate steps of O2 binding and phenol hydroxylation have been obtained for [Cu2(MeL66)]2+

Trapping tyrosinase key active intermediate under turnover

This paper shows for the first time that the spectral features of the ternary complex of tyrosinase/O2/phenol, trapped at low temperature using the very slow substrate 3,5-difluorophenol, are those of a mu-eta2:eta2-peroxidodicopper(II) species, and that this remains the only enzyme species under turnover and substrate saturation conditions

El Tlacuache Núm. 53 (2002). 53 Año 2 (2002) agosto. El Tlacuache

- Patrimonio Cultural por B. Palavicini y S.Garza. - Nuestro patrimonio desconocido por Teresita Loera y Anaite Monterforte. - El Yauhtli por Margarita Avilés y Macrina Fuentes. - Patrimonio cultural: Legislación e historia por Carlos F. Alessio-Robles

Expanding Capabilities for Epistemic Justice Through Social Innovation: The Case of Business and Management Courses in UNIMINUTO, Colombia

The chapter addresses the consideration and development of students’ competencies for social innovation in higher education by generating spaces of engagement with local communities. We combine concepts from the capability approach and epistemic injustice to address this topic and ask these specific questions: which epistemic capabilities can be generated in students when engaging with local communities in fostering social innovation processes, and how? And, how are these processes contributing to challenging epistemic injustice? To address these questions, we propose an original framework connecting ideas from Sen and Fricker and address the specific case of six pilot courses in UNIMINUTO University (Colombia), by using a qualitative methodology and information from interviews, workshops, and secondary sources. Results suggest that (1) fostering social innovation competencies by connecting teaching processes with local communities may expand epistemic capabilities; (2) very different factors, internal and external, are at play in these processes; and (3) they are also full of potential tensions and contradictions regarding their contribution to epistemic justice