ISSN:
1573-6881
Keywords:
Cytochrome oxidase
;
proteoliposome
;
respiratory control
;
membrane potential
;
pH gradient
;
cytochromec
;
oxygen
;
proton pump
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract Cytochromec oxidase oxidizes cytochromec and reduces molecular oxygen to water. When the enzyme is embedded across a membrane, this process generates electrical and pH gradients, and these gradients inhibit enzyme turnover. This respiratory control process is seen both in intact mitochondria and in reconstituted proteoliposomes. Generation of pH gradients and their role in respiratory control are described. Both electron and proton movement seem to be implicated. A topochemical arrangement of redox centers, like that in the photosynthetic reaction center and the cytochromebc 1 complex, ensures charge separation as a result of electron movement. Proton translocation does not require such a topology, although it does require alternating access to the two sides of the membrane by proton-donating and accepting groups. The sites of respiratory control within the enzyme are discussed and a model presented for electron transfer and proton pumping by the oxidase in the light of current knowledge of the transmembranous location of the redox centers involved.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00762855
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