ISSN:
1573-6881
Keywords:
Cyrochromec oxidase
;
kinetics
;
subunit composition
;
mitochondrially synthesized polypeptides
;
Euglena gracilis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract Cytochromec oxidase was purified from mitochondria ofEuglena gracilis and separated into 15 different polypeptide subunits by polyacrylamide gel electrophoresis. All 15 subunits copurify through various purification procedures, and the subunit composition of the isolated enzyme is identical to that of the immunoprecipitated one. Therefore, the 15 protein subunits represent integral components of theEuglena oxidase. In anin vitro protein-synthesizing system using isolated mitochondria, polypeptides 1–3 were radioactive labeled in the presence of [35S]methionine. This further identifies these polypeptides with the three largest subunits of cytochromec oxidse encoded by mitochondrial DNA in other eukaryotic organisms. By subtraction, the other 12 subunits can be assigned to nuclear genes. The isolatedEuglena oxidase was highly active withEuglena cytochromec 558 and has monophasic kinetics. Using horse cytochromec 550 as a substrate, activity of the isolated oxidase was rather low. These findings correlate with the oxidase activity of mitochondrial membranes. Again, reactivity was low with cytochromec 550 and 35-fold higher with theEuglena cytochromec 558. The data show that the cytochromec oxidase of the protistEuglena is different from other eukaryotic cytochromec oxidases in number and size of subunits, and also with regard to kinetic properties and substrate specificity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00762727
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