Tentative identification of insulin from hamster pancreatic homografts and pancreas of other vertebrates.

Abstract

The assay able insulin activity associated with structurally mature cheek pouch pancreatic homografts and intact pancreas of the golden hamster and other vertebrate species was characterized more definitively by biochemical procedures. Inactivation of insulin-like activity (ILA) released in vitro was achieved in the presence of optimal concentrations of l-cysteine hydrochloride and assessed by the rat epididymal fat pad (EFP) bio-assay. Pancreatic tissue was extracted with acid-ethanol by standard procedures. The extracts were fractionated on Sephadex G-75, and the resulting fractions were dialyzed and bio-assayed by the EFP and a standard radioimmunoassay procedure. ILA was inactivated by a concentration of cysteine which abolished the action of 500 mU/ml pure bovine insulin in stimulating glucose uptake by the EFP without influencing the base line rate. Fractionated pancreatic extracts yielded consistently a protein fraction similar in elution characteristics to pure bovine insulin and possessing the pr...