Mixing ATP with soluble oxidized cytochrome c oxidase induces a spectral perturbation in the Soret region of the enzyme. This spectral perturbation is observed at ATP concentrations similar to those found to modulate the catalytic activity of cytochrome c oxidase [Malatesta, Antonini, Sarti & Brunori (1987) Biochem. J. 248, 161-165]. The process is reversible and corresponds to a simple binding...

The effects of digitonin and tocopherol on bovine heart reduced diphosphopyridine nucleotideand succinate-cytochrome c reductases and cytochrome c oxidase have been studied with the following results. 1. Low concentrations of digitonin stimulate succinateand DPNH-cytochrome c reductase and cytochrome c oxidase. Higher concentrations of digitonin completely inhibit cytochrome c reductases, while...

Cytochrome c oxidase has been found to be localized in a lipoprotein matrix in the mitochondrial membrane (l), which is undoubtedly responsible for the particulate nature of this enzyme when isolated from the tissue. Marinetti, Scaramuzzino, and Stotz (2) found that a purified cytochrome oxidase preparation contained 33% lipid which consisted of neutral fat, cholesterol, and phospholipids. The ...

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...

Cytochrome c oxidase from bakers’ yeast contains three mitochondrially made subunits (I to III) which are relatively hydrophobic and four cytoplasmically made subunits (IV to VII) which are relatively hydrophilic (Mason. T. L., Poyton, R. O., Wharton, D. C., and Schatz, G. (1973) J. Biol. Chem. 248, 1346-1354 and Poyton, R. O., and Schatz, G. (1975) J. Biol. Chem. 250, 752-761. In order to expl...

Few studies on purified bacterial reduced diphosphopyridine nucleotide (DPNH) or cytochrome oxidases have been reported, although cytochrome reduction by DPNH’ in crude bacterial extracts has repeatedly been described (l-6). Dolin (7, 8) purified a flavoprotein DPNH oxidase and peroxidase from Streptococcus jaecalis, and Lenhoff and Kaplan (9) and Lenhoff et al. (10) described the characteristi...

Cytochrome c release from mitochondria induces caspase activation in cytosols; however, it is unclear whether the redox state of cytosolic cytochrome c can regulate caspase activation. By using cytosol isolated from mammalian cells, we find that oxidation of cytochrome c by added cytochrome oxidase stimulates caspase activation, whereas reduction of cytochrome c by added tetramethylphenylenedia...

the effect of annona squamosa, lawsonia inermis and their combination with other herbal molluscicides were studied on different enzyme activity in the nervous tissue of lymnaea acuminata. twenty-four hour in vivo exposure to 40% and 80% of 24 h lc50 of plant derived molluscicides and their combination with other molluscicides such as cedrus deodara, azadirachta indica oil, allium sativum, polia...

A two-dimensional electrophoretic method which takes advantage of the "migration anomalies" experienced by some polypeptides on gels of different porosities has been successfully used to resolve the seven subunit polypeptides of yeast cytochrome c oxidase and the nine polypeptides associated with bovine cytochrome c oxidase. The two-dimensional maps provided by this method reveal clear differen...

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...