Effects of large anphiphilic ligands upon the spectra and kinetics of cytochrome C oxidase

Cytoch ro me c oxidase (ferrocytochrome c : 02 oxidoreductase ; EC 1.9. 3.1) is the terminal enzyme in the mitochondrial electron transport chain, catalyzing the transfer of electrons from ferrocytochrome c to molecular oxygen. The effects of two large amphiphilic molecules .. valinomycin and dibucaine upon the spectra of the isolated enzyme and upon the activity of both isolated enzyme and enzyme in membrane systems are investigated by using spectrophotometric and oxygen electrode techniques. The results show that both valinomycin and dibucaine change the Soret region of the spectrum and cause a partial inhibition in a concentration range higher than that in which they act as ionophores. It is concluded that both valinomycin and dibucain~ binding induce a conformational change of the protein structure which modifies the spectrum of the a3 CUB centre and diminishes the rate of electron transfer between cytochrome a and the binuclear centre.

Synthesis and spectral studies of methyl heterocylic systems

2-Carboxy-2?-methyldiphenyl sulfide was prepared by the Ullmann reaction and cyclodehydrated by sulfuric acid to afford 4-methylthioxanthone. 1-Methylthioxanthone was separated from the reaction mixture obtained upon cyclodehydration of 2-carboxy-3f-methyldiphenyl sulfide. In addition, 1-, 2-, 3- and 4-methylthioxanthone 10,10-dioxides were synthesized by oxidation of the corresponding thioxanthones. o-, m- and p-N-Tolylanthranilic acids were prepared by the Ullmann reaction and used as precursors for the preparation of 1-, 2- and 4- methyl-9-chloroacridine and finally 1-, 2-, 3- and 4-methylacridone. High resolution, 60 MHz PMR spectra were obtained on the four monomethyl isomers of xanthone, thioxanthone, thioxanthone 10,10-dioxide and acridone, and on 1-, 2- and 4-methyl-9-chloroacridine. For some compounds, coupling of all three different aromatic protons to the methyl was observed, two of the couplings typically being smaller than the third. With the large (ortho) coupling being on the order of 0.5 to 1.0 Hz, it was necessary to decouple the aromatic part of the spectrum. The magnitude of the ortho benzylic constant may be related to an incomplete Tr-bond delocalization in the molecules.

Effects of large anphiphilic ligands upon the spectra and kinetics of cytochrome C oxidase

Cytoch ro me c oxidase (ferrocytochrome c : 02 oxidoreductase ; EC 1.9. 3.1) is the terminal enzyme in the mitochondrial electron transport chain, catalyzing the transfer of electrons from ferrocytochrome c to molecular oxygen. The effects of two large amphiphilic molecules - valinomycin and dibucaine upon the spectra of the isolated enzyme and upon the activity of both isolated enzyme and enzyme in membrane systems are investigated by using spectrophotometric and oxygen electrode techniques. The results show that both valinomycin and dibucaine change the Soret region of the speetrum and cause a partial inhibition in a concentration range higher than that in which they act as ionophores. It is concluded that both valinomycin and dibucaine binding induce a conformational change of the protein structure which modifies the spectrum of the a3 CUB centre and diminishes the rate of electron transfer between cytochrome a and the binuclear centre.

Finding the Open Spaces in Closed Systems: An Exploration of Critical Pedagogy with a Social Justice Directive in an Ontario Secondary School Classroom

This study examines the first experience of students, teachers, and an administrator in implementing a teacher-designed Leadership in Social Justice Program at a large urban Ontario secondary school. The program aimed to infuse a Freirean concept of critical pedagogical praxis (Freire, 1970/1993) in a grade 12 integrated educational experience with a social justice directive. Data were collected through two questionnaires and eight in-depth interviews. The data identified three areas of awareness that described ways in which student participants were impacted most profoundly (a) developing self-awareness, (b) understanding a new educational paradigm, and (c) finding a place in the world. The study found that the program was successful in highlighting the possibility for more meaningful education and engaged many students deeply; however, its success was limited by the lead teacher’s failure to fully grasp and implement tenets of Freirean critical pedagogy that involved the role of the teacher in pedagogical processes.