Effects of different batches of /sup 125/iodine on properties of /sup 125/I-hFSH and characteristics of radioligand-receptor assays

Journal Article · Sun Feb 01 04:00:00 EST 1987 · Anal. Biochem.; (United States)

DOI:https://doi.org/10.1016/0003-2697(87)90072-8· OSTI ID:6409068

Melson, B E; Sluss, P M; Reichert, Jr, L E

Radioiodination of highly purified human follicle-stimulating hormone (hFSH) (4000 IU/mg) was performed every other week for 23 weeks using 2 mCI carrier free Na/sup 125/I (Amersham Corp., 15 mCi/micrograms I2) in the presence of lactoperoxidase. Incorporation of /sup 125/I into hFSH was determined by the method of R. C. Greenwood, W. M. Hunter, and J. S. Grover (1963) Biochem. J. 89, 114). Hormone binding was studied in vitro under steady-state conditions (16 h, 20 degrees C) using different calf testis membrane preparations having similar receptor characteristics. Each /sup 125/I-hFSH preparation was characterized for maximum bindability, specific activity of bindable radioligand as determined by self-displacement analysis, and by determination of Ka and Rt. Incorporation of /sup 125/I into FSH was relatively constant over the large number of experiments (62.4 +/- 6.4 microCi/micrograms; n = 23). By comparison, however, specific radioactivity of the receptor bindable fraction of /sup 125/I-hFSH was related to the lot of /sup 125/I utilized, and was significantly (P less than or equal to 0.01) lower and more variable (28.7 +/- 10.5 microCi/micrograms). Maximum bindability of /sup 125/I-hFSH was not correlated to specific activity (r = 0.06) but was negatively correlated to hFSH /sup 125/I incorporation (r = -0.47; P less than or equal to 0.05). These observations demonstrate the need to assess the quality of each batch of radioligand before undertaking radioligand-receptor assays and suggest that differences in Na/sup 125/I lots affect specific radioactivity of the radioligand and its receptor binding characteristics.

• Research Organization: Albany Medical College of Union Univ., NY
• OSTI ID: 6409068
• Journal Information: Anal. Biochem.; (United States), Journal Name: Anal. Biochem.; (United States) Vol. 2; ISSN ANBCA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CHEMICAL PROPERTIES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
FSH
GONADOTROPINS
HORMONES
IN VITRO
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGANDS
MEMBRANE PROTEINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PITUITARY HORMONES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
TRACER TECHNIQUES