# Study on the Relationship between Particulate Methane Monooxygenase and Methanobactin on Gold-Nanoparticles-Modified Electrodes

## TL;DR

This study explores how methanobactin helps particulate methane monooxygenase interact with gold electrodes, enabling better electron transfer and enzyme stability.

## Contribution

The study introduces methanobactin as a novel electron transporter and stabilizer for pMMO in bioelectrochemical systems.

## Key findings

- Electron transfer parameters α and ks are higher in environments with only CH4 or O2.
- In CH4 and O2 environments, pMMO undergoes a two-electron transfer process with lower α and ks.
- Methanobactin stabilizes pMMO and maintains its redox state, enabling methane oxidation.

## Abstract

(1) Background: Particulate methane monooxygenase (pMMO) has a strong dependence on the natural electron transfer path and is prone to denaturation, which results in its redox activity centers being unable to transfer electrons with bare electrodes directly and making it challenging to observe an electrochemical response; (2) Methods: Using methanobactin (Mb) as the electron transporter between gold electrodes and pMMO, a bionic interface with high biocompatibility and stability was created. The Mb-AuNPs-modified functionalized gold net electrode as a working electrode, the kinetic behaviors of pMMO bioelectrocatalysis, and the effect of Mb on pMMO were analyzed. The CV tests were performed at different scanning rates to obtain electrochemical kinetics parameters. (3) Results: The values of the electron transfer coefficient (α) and electron transfer rate constant (ks) are relatively large in test environments containing only CH4 or O2. In contrast, in the test environment containing both CH4 and O2, the bioelectrocatalysis of pMMO is a two-electron transfer process with a relatively small α and ks; (4) Conclusions: It was inferred that Mb formed the complex with pMMO. More importantly, Mb not only played a role in electron transfer but also in stabilizing the enzyme structure of pMMO and maintaining a specific redox state. Furthermore, the continuous catalytic oxidation of natural substrate methane was realized.