Thermal Denaturation of Alpha1-Protease Inhibitor

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Abstract
Alpha1-protease inhibitor (α1Pl), also called α1-antitrypsin, may be useful for replacement therapy in a number of chronic or acute disorders. The risk associated with the possible presence of hepatitis virus can be greatly reduced by pasteurization at 60° C for 10 h. A series of thermal denaturation profiles was obtained in the presence of various protein stabilizers using the increase in 1,8-anilinonaphthalene sulfonate fluorescence that accompanies protein denaturation. A parallel series of experiments was conducted to evaluate each additive for its capacity to protect the biological activity of α1Pl. As much as 92% of the inhibitory activity against elastase and trypsin could be recovered after pasteurization in buffer containing citrate (1.2 M) and either EDTA (0.5 M) or gluconate (1.2 M). Loss of activity was not affected by protein concentration. In conclusion, conditions have been developed to protect the bulk of α1PI from denaturation during pasteurization, and this should give an added impetus to efforts to test the efficacy of this protein in various clinical conditions.