Abstract
We have succeeded in obtaining insulin in crystalline form with relative ease from the islets of fishes. These crystals are practically identical in physiological activity and in sulphur content with the crystals prepared from beef insulin.
The crystallization of insulin from pig's pancreas is more difficult. About 2 years ago Professor Abel encountered difficulties in crystallizing insulin from several of the Lilly preparations. He subsequently learned that these extracts had been made from the pancreatic tissue of both pigs and beeves. Following this observation extracts made only from the pancreas of beeves were used until the present opportunity of working with extracts made from the islet tissue of fishes 1 and from the pancreas of the pig, 2 presented itself. We have now succeeded in obtaining crystalline insulin from an extract made from pig's pancreas only. The main difficulty appears to us at present to be due to the higher content of fats and lipoids in pig's pancreas. It seems advisable to use beef pancreas exclusively to readily obtain crystalline insulin, unless fish islets can be obtained in considerable amounts.
It might be added that the crystallization of the products referred to above is effected by the methods previously described in papers on insulin from this laboratory and that the methods of defatting pancreatic extracts made from the pig's pancreas are those generally used.
Further detailed studies are now in progress, and at a later date a comprehensive paper will be published.
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