Methane, a greenhouse gas with a global warming potential more than 30 times that of carbon dioxide, undergoes a natural reaction that converts it into the useful resource methanol. However, the mechanism by which this reaction proceeds remained an unresolved scientific problem for a long time.

This 'miracle of nature' has finally been revealed by the research team of Professor Seungjae Lee at Jeonbuk National University (JBNU) (graduate students Yunha Hwang and Soyeon Park). Using cryo-electron microscopy (cryo-EM), the team determined, at atomic resolution, the structure and operating mechanism of the protein complex that converts methane into methanol in nature.

The results of this study were published online in the latest issue of the international journal Advanced Science.

Methane is a potent greenhouse gas but also a resource that can be widely used, for example as a fuel. In nature, a protein called soluble methane monooxygenase (sMMO), possessed by some microorganisms, catalyzes the conversion of methane to methanol. However, exactly how this protein moves and initiates the reaction has not been precisely determined until now.

Conventional X-ray crystallography requires proteins to be analyzed in a fixed crystalline state, which limits the observation of the movements of proteins as they operate in aqueous environments.

To overcome these limitations, Professor Lee's team adopted cryo-EM techniques. This method rapidly freezes proteins below -180°C, allowing observation of structures that closely resemble their natural state. Through this approach, the researchers were able to observe, step by step, how the complex—composed of more than seven polypeptide chains—repeatedly associates and dissociates to convert methane to methanol.

For the first time, they scientifically explained the structural changes and sequence of events by which the methane oxidation reaction—previously only described as occurring 'naturally'—actually proceeds.

The study was carried out jointly by domestic and international researchers centered at JBNU. The first author, graduate student Yunha Hwang, collaborated with researchers at the Institute for Basic Science (IBS) (Dr. Beomhan Ryu) and the University of Maryland School of Medicine (Professor Edwin Pozharski) to perform high-resolution structural analyses. The work also serves as an example that regional national universities can lead world-class basic scientific research.

Professor Seungjae Lee explained the significance of the research, saying, 'We expect these results to serve as foundational data for the production of eco-friendly fuels from methane and for the development of artificial catalysts,' and added, 'The findings are particularly meaningful because they could lead to technologies that both reduce greenhouse gases and enable their use as resources.'

This research was supported by the JBNU Glocal TOP100 Project, the National Research Foundation of Korea, and the C1 Gas Refinery Project Group.