(/sup 125/I)diiodoinsulins. Binding affinities, biologic potencies, and properties of their decay products

Journal Article · Thu Jul 01 04:00:00 EDT 1982 · Diabetes; (United States)

OSTI ID:6192853

Perez Maceda, B; Linde, S; Sonne, O; Gliemann, J

Insulin was iodinated with 0.3-0.4 mol /sup 125/I/mol insulin using the lactoperoxidase method. About one-third of the radioactivity incorporated into insulin was in diiodoinsulins and about 40% of these molecules contained diiodotyrosine in residue 14 of the A chain. Most of the remaining molecules contained one A14-monoiodotyrosine and one monoiodotyrosine in either position A19, B16, or B26. The binding affinity and biologic potency of this heterogeneous diiodoinsulin preparation was not significantly different from that of A14-(/sup 125/I)monoiodoinsulin in rat adipocytes, whereas it was slightly reduced in hepatocytes and IM-9 lymphocytes. From the iodine distribution and previous data on the binding affinity of each of the four monoiodoinsulin isomers it was calculated that A14-diiodotyrosine-insulin possesses full binding affinity and biologic potency in adipocytes. Diiodoinsulins isolated from another iodoinsulin preparation (iodate method) contained 58% A19-diiodotyrosine-insulin, and most remaining molecules contained one A19-monoiodotyrosine. The binding affinity of this mixed diiodoinsulin preparation was approximately one-fourth of that of A14-monoiodoinsulin in adipocytes, IM-9 lymphocytes, and hepatocytes. It was calculated that A19-diiodotyrosine-insulin is nearly devoid of binding affinity. The diiodoinsulins (lactoperoxidase method) decayed to iodide (probably from diiodotyrosine-insulin) or to polymers with little specific but a markedly increased nonspecific binding. In addition, the polymers had a marked tendency to adsorb to cellulose acetate filters. Conclusions: 1. The binding affinities of diiodoinsulins range from very low values to values at least as high as that of insulin depending on the positions of the iodine moieties. 2. The relative binding affinities vary among tissues. 3. Polymeric decay products give high nonspecific binding.

• Research Organization: Institute of Physiology, University of Aarhus, Universitetsparken, Denmark
• OSTI ID: 6192853
• Journal Information: Diabetes; (United States), Journal Name: Diabetes; (United States) Vol. 31:7; ISSN DIAEA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702 -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMISTRY
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CHEMICAL BONDS
CHEMICAL REACTIONS
CHEMISTRY
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
FAT CELLS
HALOGENATION
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINATION
IODINE 125
IODINE ISOTOPES
ISOTOPES
LABELLING
LEUKOCYTES
LIVER CELLS
LYMPHOCYTES
MAMMALS
MATERIALS
NUCLEI
ODD-EVEN NUCLEI
PEPTIDE HORMONES
RADIOCHEMISTRY
RADIOISOTOPES
RATS
RODENTS
SOMATIC CELLS
VERTEBRATES