The calcium binding site, which is located inside the molecule (particularly under the active site, if it is placed in accordance with the picture provided) is formed by the oxygen of the main chain residues 297, 345 and 348, as well as by the oxygen of the side chain of Asp324 [1, 6]. Additionally, this site is formed by a.a. 293, 347, 111-115 and 139-143 [8].