Cytochrome c oxidase from bovine heart binds Ca(2+) reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca(2+) shifts the absorption spectrum of heme a, which allowed previously to determine the kinetics and equilibrium characteristics of the binding. However, no effect of Ca(2+) on the functional characteristics of cytochrome oxidase was reve...

Despite the efforts made to identify Pseudomonas aeruginosa by saccharolytic methods, this gram-negative microorganism remains predominately a proteolytic bacillus with weak saccharolytic activity. Pigmentation, growth temperature, pellicle formation and other minor characteristics are unsatisfactory laboratory diagnostic criteria (Gaby, 1946, 1955; Gaby and Free, 1953). Needless to say it is h...

The respiratory effector molecules carbon monoxide (CO), nitrous oxide (N 20), and deuterium oxide (D20) were used to probe cytochrome c oxidase (EC 1.9.3.1) activity in mitochondrial particles and enzyme isolated from germinating bean seeds. Mitochondrial CO effects were dose-dependent and readily reversible, with maximal activity inhibition of 58% and 81% for mitochondria and oxidase, respect...

Bile salts are commonly used in the isolation and purification of the lipid-rich respiratory enzymes. Wainio et al. (1, 2) found sodium deoxycholate to be particularly effective in the preparation of a soluble cytochrome c oxidase. Other workers have utilized sodium cholate (3). The use of both of these agents in the extraction of an insoluble heart muscle preparation made by the method of Keil...

Cytochrome c oxidase catalyzes the reduction of oxygen to water. This process is accompanied by the vectorial transport of protons across the mitochondrial or bacterial membrane ("proton pumping"). The mechanism of proton pumping is still a matter of debate. Many proposed mechanisms require structural changes during the reaction cycle of cytochrome c oxidase. Therefore, the structure of the cyt...

The activity of reconstituted cytochrome-c oxidase (EC 1.9.3.1) from bovine heart is stimulated by intraliposomal ADP but not by NaCl of the same ionic strength. A monoclonal antibody which reacts with subunits VIa-H (heart-type) and VIc, due to the evolutionary relationship between these subunits, also stimulates the activity of the enzyme from bovine heart but not from bovine liver. The antib...

Fluorescence resonance energy transfer was used for measuring the distances between the following three sites of purified yeast cytochrome c oxidase: (a) a highly reactive sulfhydryl group on the mitochondrially made Subunit II; (b) endogenous heme a; (c) cytochrome c bound to the mitochondrially made Subunit III. Subunit II of purified cytochrome c oxidase was stoichiometrically and covalently...

The fully oxidized complex of cytochrome c and cytochrome oxidase formed at low ionic strength was studied by resonance Raman spectroscopy. The spectra of the complex and of the individual components were compared over a wide frequency range using Soret band excitation. In both partners of the complex, structural changes occur in the heme groups and in their immediate protein environment. The s...

There is an increasing demand for the development of intermediate biomarkers to assess colon cancer risk. We previously determined that a live cell bioassay, which assesses apoptosis resistance in the nonneoplastic colonic mucosa, detects approximately 50% of patients with colon cancer. A hypothesis-driven biomarker that reflects apoptosis resistance in routine formalin-fixed, paraffin-embedded...

The repair of cytochrome oxidase depletion during the treatment of copper deficiency was studied in the rat. The purpose of this study was to distinguish the role of new cell production from the possibly more specific role of mitochondrial turnover in determining the rate of this repair. In rats on a copper-deficient regimen until 2.5-3 months of age, activities of cytochrome oxidase expressed ...