| abstract |
A method of protecting soluble proteins such that their biological activity is preserved after freezing by exposing the protein to a carbohydrate and transition metal ion prior to freezing. The protected protein can then be thawed or lyophilized and rehydrated without denaturation of impairment of the protein's biological activity. The protein is preferably exposed to the carbohydrate by placing it in a 25-100 mM aqueous solution of carbohydrate and 2 mM Z+2. This method is especially effective in preserving the biological activity of fragile proteins such as the enzyme phosphofructokinase. The present method can be used to preserve pharmaceutically useful proteins in a frozen or freeze-dried form for storage and distribution. The treated protein can be thawed or rehydrated and administered directly to a user without removing the cryoprotectant since the carbohydrates and trace amounts of many transition metal ions are nontoxic. |