Neutron Crystallography Reveals How Carbonic Anhydrases (CAs) Work
CAs are a family of enzymes that play an essential role in the metabolism of carbon dioxide by converting it into a carbonate ion and a proton. Because they are very stable and inexpensive, CAs could be used in significant large-scale applications such as carbon sequestration processes and biofuel production. However, little is known about the arrangement of the active site of CAs while they carry out their function, a gap that has impeded design of optimized CAs for these applications. Neutron crystallography experiments at the Los Alamos Neutron Science Center to determine the structure of human carbonic anhydrase II have revealed the orientation of amino acids around the zinc ion in the active site, as well as the unexpected presence of a water molecule bound to the metal ion. This structural information has enabled development of a mechanism to explain the proton transfer process and is being used to re-engineer the enzyme to be pH insensitive and thermally stable for carbon sequestration or biodiesel production.
Fisher, S. Z., et al. 2010. “Neutron Structure of Human Carbonic Anhydrase II: Implications for Proton Transfer,” Biochemistry 49, 415–21.