Proton Occupancies in Histidine Side Chains of Carbonic Anhydrase II by Neutron Crystallography and NMR - Differences, Similarities and Opportunities
Histidine is a key amino-acid residues in proteins that can exist in three different protonation states: two different neutral tautomeric forms and a protonated, positively charged one. It can act as both donor and acceptor of hydrogen bonds, coordinate metal ions, and engage in acid/base catalysis. Human Carbonic Anhydrase II (HCA II) is a pivotal enzyme catalyzing the reversible hydration of carbon dioxide. It contains 12 histidine residues: six surface exposed, two buried, three active site...
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