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A new procedure for the preparation of crystalline pancreatic amylase from swine is described briefly. The new method offers several distinct advantages over earlier methods reported for the purification and crystallization of pancreatic amylase. The yields of highly active crystalline amylase are materially increased while the new process is much less laborious and much less time consuming than earlier procedures. Additional properties of crystalline pancreatic amylase not previously reported are presented and discussed.

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The stability and the activity of pancreatic amylase are exceedingly sensitive to its chemical environment. This paper reports additional observations concerning some of the factors concerned. The work was carried out with three times crystallized electrophoretically homogeneous amylase. The factors studied include: the influence of the pH of its aqueous solutions upon the stability of the amylase at different temperatures; the influence of the concentration of the amylase upon its stability in aqueous solution; the influence of calcium and of chloride ions upon the stability and upon the activity of the amylase. Previous evidence has shown that pancreatic amylase requires certain anions for its action and that chloride ions are outstanding in this respect. These findings have been confirmed and extended. Chloride ions also protect the amylase from inactivation in aqueous solution. On the other hand, while calcium ions also protect pancreatic amylase from inactivation in aqueous solution, they have no influence upon the activity as distinguished from the stability of the amylase. The evidence makes it clear that there is a fundamental difference between the protection of the amylase from loss of activity, a protection which, under the conditions studied is exerted to very nearly the same extent by chloride and by calcium ions, and the activation of the amylase by chloride and by certain other anions. This difference is being investigated.