Related Experiment Videos
The Paracoccus denitrificans cytochrome aa3 has a third subunit.
T Haltia1, A Puustinen, M Finel
1Department of Medical Chemistry, University of Helsinki.
European Journal of Biochemistry
|March 15, 1988
Summary
A third polypeptide subunit was identified in Paracoccus cytochrome c oxidase. This protein binds dicyclohexylcarbodiimide and matches the COIII gene product, indicating a three-subunit structure.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- Paracoccus cytochrome c oxidase is a key enzyme in bacterial respiration.
- Previous studies suggested a multi-subunit structure for this enzyme.
- The exact composition and function of all subunits were not fully elucidated.
Purpose of the Study:
- To identify and characterize the subunits of Paracoccus cytochrome c oxidase.
- To determine if a third polypeptide subunit exists and its role.
- To compare the Paracoccus enzyme structure to eukaryotic cytochrome c oxidases.
Main Methods:
- Enzyme purification from aerobically grown Paracoccus membranes.
- Dicyclohexylcarbodiimide (DCC) binding assays to identify specific subunits.
- N-terminal amino-acid sequencing of the DCC-binding protein.
- Comparison of N-terminal sequence with known gene products.
Main Results:
- Demonstrated the presence of a third polypeptide subunit (23 kDa) in Paracoccus cytochrome c oxidase.
- This 23 kDa subunit was shown to bind dicyclohexylcarbodiimide in both bacterial membranes and the purified enzyme.
- The N-terminal amino-acid sequence of this subunit is identical to the deduced sequence of the COIII gene product.
Conclusions:
- Paracoccus cytochrome c oxidase is composed of at least three subunits.
- The identified 23 kDa subunit corresponds to the COIII gene product.
- This finding supports the analogy between bacterial aa3-type oxidases and the three mitochondrially coded polypeptides in eukaryotic enzymes.