Researchers from the University of Liverpool, Japan, and Argentina have captured atomic-resolution images of an important copper-containing enzyme using advanced X-ray Free Electron Laser (XFEL) technology at SACLA in Japan. XFEL technology generates ultra-bright, ultra-short X-ray pulses, enabling atomic-scale imaging and real-time observation of chemical, biological, and physical processes.

The international team—led by Dr. Svetlana Antonyuk and Professor Samar Hasnain at the University of Liverpool, Professor Takehiko Tosha at the University of Hyogo, and Dr. Masaki Yamamoto at RIKEN SPring-8—studied a protein that plays a key role in the global nitrogen cycle. This protein converts nitrite, an essential nitrogen intermediate, into nitric oxide gas.

The new details reveal how an enzyme called copper nitrite reductase (CuNiR) from three different organisms converts nitrite to nitric oxide gas, using an electron and a proton—a vital process for both biology and the environment.