Patent ID: 8486388

Claim:
An aqueous composition comprising: (i) a metalloprotein whose biological activity or three dimensional structure is dependent on retention of calcium ions in a binding site within the protein; (ii) calcium ions at a concentration of 0.01 to 20 mM; (iii) weak ligand buffers TRIS and benzoate, each having a stability constant measured at 25° C. for a complex with calcium ion log K<0.5; and (iv) a tonicity modifier which is a weak ligand having a stability constant measured at 25° C. for a complex with calcium ion log K<0.5; wherein said composition is substantially free of excipients which are medium-strength ligands having a stability constant measured at 25° C. for a complex with calcium ion log K between 0.5 and 2, and is substantially free of excipients in free form which are strong ligands having a stability constant measured at 25° C. for a complex with calcium ion log K>2.