Microheterogeneous forms of radioiodinated bovine thyrotropin: discrimination of different receptor-active components by gel permeation chromatography

Journal Article · Wed Jan 01 04:00:00 EST 1986 · Endocrinology; (United States)

DOI:https://doi.org/10.1210/endo-118-1-14· OSTI ID:5952302

Stanton, P G; Hearn, M T

The products of the radioiodination and subsequent receptor adsorption of bovine TSH (bTSH) radiolabeled by the lactoperoxidase method have been further investigated. After receptor adsorption, (125I)bTSH was resolved by gel permeation chromatography on Sephadex G-100 (superfine) under low ionic strength conditions into three peaks of radioactivity (tracers 2a, 2b, and 2c, respectively). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions demonstrated that each tracer component was radiolabeled on both the alpha- and beta-subunits. Analysis of the three tracers by TSH radioreceptor assay (under different radioreceptor assay conditions) showed that tracers 2b and 2c exhibited saturable rebinding to crude thyroid membranes containing functional TSH receptors. However, tracer 2c exhibited a maximum binding 2-fold greater than tracer 2b. This difference has been attributed to the abundance of an apparently low affinity binding component in tracer 2c. Rechromatography of tracers 2b and 2c on Sephadex G-100 (superfine) under high ionic strength conditions yielded tracer profiles that were coincident, demonstrating that the initial separation under low ionic strength conditions was not based on differences in molecular volume. The data indicate that radioiodination of highly purified bTSH yields multiple tracer components. Further, receptor adsorption, commonly used to purify freshly iodinated bTSH before radioreceptor assay, purifies at least two species of receptor-active (125I) bTSH.

• Research Organization: St. Vincent's Institute of Medical Research, Melbourne, Australia
• OSTI ID: 5952302
• Journal Information: Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 1; ISSN ENDOA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400105 -- Separation Procedures
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ADSORPTION
ANIMALS
BETA DECAY RADIOISOTOPES
CATTLE
CHEMICAL ANALYSIS
CHEMICAL BONDS
CHEMICAL REACTIONS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
HALOGENATION
HORMONES
INTERMEDIATE MASS NUCLEI
IODINATION
IODINE 125
IODINE ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
LABELLING
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
OXIDOREDUCTASES
PEPTIDE HORMONES
PEROXIDASES
PITUITARY HORMONES
RADIOASSAY
RADIOISOTOPES
RUMINANTS
SEPARATION PROCESSES
SORPTION
TSH
VERTEBRATES