Zhu X, Aoyama E, Birk AV, Onasanya O, Carr WH, Mourokh L, Minteer SD, Vittadello M. Cytochrome c oxidase oxygen reduction reaction induced by cytochrome c on nickel-coordination surfaces based on graphene oxide in suspension.
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020;
1861:148262. [PMID:
32673675 DOI:
10.1016/j.bbabio.2020.148262]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 07/01/2020] [Accepted: 07/07/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND
The electrochemical and spectroscopic investigation of bacterial electron-transfer proteins stabilized on solid state electrodes has provided an effective approach for functional respiratory enzyme studies.
METHODS
We assess the biocompatibility of carboxylated graphene oxide (CGO) functionalized with Nickel nitrilotriacetic groups (CGO-NiNTA) ccordinating His-tagged cytochrome c oxidase (CcO) from Rhodobacter sphaeroides.
RESULTS
Kinetic studies employing UV-visible absorption spectroscopy confirmed that the immobilized CcO oxidized horse-heart cytochrome c (Cyt c) albeit at a slower rate than isolated CcO. The oxygen reduction reaction as catalyzed by immobilized CcO could be clearly distinguished from that arising from CGO-NiNTA in the presence of Cyt c and dithiothreitol (DTT) as a sacrificial reducing agent. Our findings indicate that while the protein content is about 3.7‰ by mass with respect to the support, the contribution to the oxygen consumption activity averaged at 56.3%.
CONCLUSIONS
The CGO-based support stabilizes the free enzyme which, while capable of Cyt c oxidation, is unable to carry out oxygen consumption in solution on its own under our conditions. The turnover rate for the immobilized CcO was as high as 240 O2 molecules per second per CcO unit.
GENERAL SIGNIFICANCE
In vitro investigations of electron flow on isolated components of bacterial electron-transfer enzymes immobilized on the surface of CGO in suspension are expected to shed new light on microbial bioenergetic functions, that could ultimately contribute toward the improvement of performance in living organisms.
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