Neutron Crystallography Helps Understand How CO2 Metabolizing Enzymes Work

The Science

Carbonic anhydrases (CAs) are a family of enzymes that play an essential role in the metabolism of carbon dioxide, converting CO2 into carbonate ion and a proton. CAs are very stable and inexpensive, and could find significant large-scale applications in carbon sequestration processes and biofuel production. However, little is known about the active site of CAs while they carry out their function, impeding design of optimized CAs for these applications. Now scientists at Los Alamos National Laboratory and the University of Florida have used neutron crystallography to determine the structure of human carbonic anhydrase II (HCA II). Human carbonic anhydrase II (HCA II) catalyzes the reversible hydration of carbon dioxide to form bicarbonate and a proton. Their experiments reveal the orientation of the amino acids around the zinc ion in the active site and the unexpected presence of a water molecule bound to the metal ion. The structural information has enabled development of a mechanism to explain the proton transfer process. The scientists used the DOE-funded Protein Crystallography Station (PCS) at Los Alamos for their research.


Zoë Fisher, S., A. Y. Kovalevsky, J. F. Domsic, M. Mustyakimov, R. McKenna, D. N. Silverman, and P. A. Langan. 2010. “Neutron Structure of Human Carbonic aAnhydrase II: Implications for Proton Transfer,” Biochemistry 49, 415–21. DOI:10.1021/bi901995n.