A study of the kinetics of the oxidation of cytochrome c by cytochrome c oxidase

Smith, Lucile; Conrad, H.R.

doi:10.1016/0003-9861(56)90055-8

Cited by 282 publications

(64 citation statements)

References 23 publications

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“…Cytochrome oxidase activity was measured spectrophotometrically at 25 "C by following the decrease of absorbance at 550 nm of ferrocytochrome c (50 pM) in 0.1 M Tris-acetate buffer pH 8.0 [14].…”

Section: Assay Of Cytochrome Oxidase Activitymentioning

confidence: 99%

Cycloheximide Resistant Incorporation of Amino Acids into a Polypeptide of the Cytochrome Oxidase of Neurospora crassa

Weiss¹,

Sebald²,

Bücher³

1971

European Journal of Biochemistry

124

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Radioactive leucine was incorporated by Neurospora crmsa mitochondria in vivo in the presence of cycloheximide. When the membrane protein of these mitochondria was chromatographically separated on oleyl polymethacrylic acid resin, a number of fractions were obtained which differ with respect to their contents of radioactivity and cytochromes. The highest specific radioactivity was found in the fraction containing cytochrome aa3. This fraction proved to be a pure and enzymatically active cytochrome oxidase. Its ratio of absorbance a t 280 nm (ox)/ 443 nm (red.) was 2

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Section: Assay Of Cytochrome Oxidase Activitymentioning

confidence: 99%

Cycloheximide Resistant Incorporation of Amino Acids into a Polypeptide of the Cytochrome Oxidase of Neurospora crassa

Weiss¹,

Sebald²,

Bücher³

1971

European Journal of Biochemistry

124

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“…Horse heart cytochrome c (type VI) was purchased from Sigma Chemical Co. A stock solution of ferricytochrome c was dialyzed against three changes of 20 mM Tris base and 10 ,uM EDTA to remove bound ions (8). Immediately after dialysis the preparation was chromatographed on a Sephadex G-75 column equilibrated with 0.1 M 2-(N-morpholino)ethanesulfonic acid (Mes), pH 6, and 10,uM EDTA.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the acceptor, oxidase, was always available and oxygen was not limiting in the reaction. All experiments were performed in the presence of 0.1 M Mes, pH 6, and 10 The pseudo-first order nature of the steady state kinetics requires the general form for the rate equation to be:…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, the apparent inhibition by cytochrome c is independent of the oxidation state of the cytochrome c. Smith and Conrad have interpreted the inhibition of the reaction by total cytochrome c in terms of the formation of inactive complexes of cytochrome c with the oxidase. The possibility of inactive complex formation, together with the observed nonsaturation kinetics, has led these workers to suggest that Km and Vmax may not be meaningful parameters in analysis of the oxidase reaction (10 Biochemistry: Errede et al The formal mechanisms and rate laws deduced and previously proposed (12,(14)(15)(16)(17) have considered only one binding site for cytochrome c on the oxidase, and require that linear double reciprocal plots should result for all cytochrome concentrations. Any of the five mechanisms proposed by Minneart (12) as well as that proposed by Yonetani and Ray (16) Table 3 extends the mechanism proposed by Nicholls (15) to include such dead-end complex formation with both ferri-and ferro-cytochrome c and to include two binding sites on the oxidase.…”

Section: Methodsmentioning

confidence: 99%

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Oxidation of ferrocytochrome c by mitochondrial cytochrome c oxidase.

Errede¹,

Haight²,

Kamen³

1976

Proc. Natl. Acad. Sci. U.S.A.

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Attempts to rationalize the kinetics of cytochrome c oxidation catalyzed by solubilized mitochondrial cytochrome c oxidase (ferrocytochrome c-.oxygen oxidoreductase, EC 1.9.3.1) have been based on assumptions of productive complex formation (Michaelis-Menten approach). However, the range of substrate concentrations used has not, in general, been sufficient to establish a general rate equation. Data adequate to derive such a rate expression are presented, as well as a method for estimation of constants which appear in the rate law deduced and reported herein. It is shown that either of two types of mechanisms, one assuming productive complex formation, as opposed to the other postulating dead-end complex formation, accurately predict the rate equation as deduced from experiment.

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“…The reaction mixture contained 94.8 mM Tris base, 95.6 µM DTNB, 50 mM acetyl-CoA, 1.2 mM oxaloacetate and 30 µL of supernatant in a total volume of 1 mL. The COX activity was determined according to Smith and Conrad (1956) with 20 µL of homogenate in 1 mL of a reaction mixture that contained 90 µM reduced cytochrome C as substrate and 50 mM potassium phosphate. The oxidation of cytochrome c was measured at 550 nm.…”

Section: Metabolic Enzyme Activitiesmentioning

confidence: 99%

Compositional, organoleptic, metabolic enzyme activity and fibre characteristics of muscle from bulls with different growth paths to a common carcass weight

et al. 2018

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The proximate composition, organoleptic quality, metabolic enzyme activity and fibre characteristics of longissimus thoracis muscle from suckler bulls assigned to three target indoor winter (from 9 to 13 months of age approximately) growth rates (average daily gain of 0.6, 1.0 and 1.5 kg; n = 14/group) were investigated. The feeding regimes to achieve the target average daily gains were 2, 4 and 6 kg of concentrate respectively, plus grass silage ad libitum. The duration of the winter feeding period was 123 days, after which bulls were turned out to pasture and grazed for 99 days before re-housing and finishing on concentrates ad libitum plus grass silage until they reached a liveweight to yield a target carcass weight of 380 kg. The average daily gain during the grazing period was higher (P < 0.001) for the 0.6 than for the 1.0 and 1.5 average daily-gain groups, which did not differ. Proximate composition, collagen content, metabolic enzyme activity and fibre-type distribution of the longissimus thoracis muscle were similar (P > 0.05) between the 0.6, 1.0 and 1.5 average daily-gain groups. Apart from tenderness, which was rated higher (P < 0.05) for the 0.6 group than for the 1.0 average daily-gain group, the sensory characteristics of the beef were not influenced by the different winter growth rates applied. Overall, restricting the growth rate during winter had little effect on subsequent beef appearance or eating quality.

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A study of the kinetics of the oxidation of cytochrome c by cytochrome c oxidase

Cited by 282 publications

References 23 publications

Cycloheximide Resistant Incorporation of Amino Acids into a Polypeptide of the Cytochrome Oxidase of Neurospora crassa

Cycloheximide Resistant Incorporation of Amino Acids into a Polypeptide of the Cytochrome Oxidase of Neurospora crassa

Oxidation of ferrocytochrome c by mitochondrial cytochrome c oxidase.

Compositional, organoleptic, metabolic enzyme activity and fibre characteristics of muscle from bulls with different growth paths to a common carcass weight

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