Cadmium-113 Nuclear Magnetic Resonance Studies of Bovine Insulin: Two-Zinc Insulin Hexamer Specifically Binds Calcium

Abstract
By use of cadmium-113 nuclear magnetic resonance spectroscopy, a specific calcium ion binding site has been identified in the bovine two-zinc insulin hexamer. This site is composed of six glutamyl carboxylate groups clustered in the center of the hexamer, and is distinct from the normal zinc ion binding sites.