The invention provides a formulation including a buffer having a pH less than 6.0, a divalent cation between about 5-200 mM, an excipient comprising a sugar or polyol and an effective amount of a therapeutic polypeptide. Also provided is a method of stabilizing a polypeptide. The method includes contacting a therapeutic polypeptide with a concentration of divalent cation between about 5-150 150 mM in a buffer having a pH less than 6.0 and an excipient comprising a sugar or polyol.
