The unusual enzyme HDCR produces formic acid from gaseous hydrogen (H2) and carbon dioxide (CO2), thus removing CO2 from the environment and storing it in the cell. In this process, HDCR transfers electrons from hydrogen to the CO2. This is the first known enzyme that can directly use hydrogen as an electron source for CO2 storage. The enzyme HDCR was discovered in the heat-loving bacterium Thermoanaerobacter kivui, originally found in 1981 in Lake Kivu in Central Africa. It lives in environments that have little oxygen, such as the deep sea. The research teams from the Universities of Basel, Frankfurt (Prof. Volker Müller) and Marburg (Prof. Jan Schuller) have now successfully elucidated the structure of HDCR. The results have now been published in Nature.
The enzyme HDCR is composed of long filaments. This thread-like structure acts like an electron-conducting ‘nanowire’ that is evidently responsible for the extremely efficient conversion rates of the two gases. “It is the structure of the enzyme that makes high-speed CO2 storage possible,” explains Dr. Ricardo Righetto, one of the first authors of the study at the Biozentrum of the University of Basel. The researchers found this enzyme to be faster than any previously known chemical catalyst performing this reaction.