Abstract
Insulin was bound physically to DEAE-cellulose, AE-cellulose, activated carbon and aluminium silicate. The biological and immunological activities of these preparations were compared with that of standard insulin. The hydrolyses of these preparations with pepsin and α-chymotrypsin were also measured in vitro, and following results were obtained:
1). The insulin content of these preparations was increased in the following order; aluminium silicateinsulin, activated carbon-insulin, AE-cellulose-insulin and DEAE-cellulose-insulin.
2). By a successive washing procedure, insulin was shown to be fixed tightly on aluminium silicate, and loosely on AE-cellulose and activated carbon. Under the condition of pH 8.0, DEAE-cellulose bound insulin tightly.
3). The biological activity of these preparations was found to be between 50 to 70% of the original value. As compared with the biological activity, a slightly less immunoreactivity was recovered.
4). DEAE-cellulose-insulin was readily destroyed by pepsin, but relatively resistant to a-chymotrypsin. A relative resistance to peptic digestion was found in AE-cellulose-insulin. Aluminium silicate-insulin was resistant to peptic digestion. Activated carbon-insulin was quite resistant to the action of both peptic and α-chymotryptic digestions.
From these results, it is indicated that these modified insulin preparations which are not affected by peptic and α-chymotryptic digestions, might be used as a tool for studying on the enteral administration of insulin.
