Sequential degradation of insulin by rat liver homogenates.

Insulin was incubated with rat liver homogenate in the presence of glutathione. The products formed were examined by chromatography on a Sephadex G-75 column, with 50% acetic acid as eluent. The results show that insulin is degraded by rat liver homogenates in sequential order: first, a splitting of insulin into A and B chains by glutathione-insulin transhydrogenase, followed by proteolysis of the resulting polypeptides to small molecular weight components.