Monoiodoinsulin Labelled in Tyrosine Residue 16 or 26 of the Insulin B-Chain. Preparation and Characterization of some Binding Properties

Abstract

By the combination of polyacrylamide gel electrophoresis and QAE-Sephadex ion exchange chromatography it was possible to isolate the 4 isomers of porcine [125I]monoiodoinsulin to a purity of more than 97%. The yield of the 2 B-chain-labeled isomers was increased by iodinating in buffer containing 6 M urea. The apparent binding affinity to isolated rat adipocytes was 0.65 for the A19 isomer, 1.0 for the B16 isomer and 2.0 for the B26 isomer, respectively, relative to the A14 isomer. The B26 isomer had only an apparent binding affinity of 1.2 relative to the A14 isomer in isolated hepatocytes.