Effect of iodination on human growth hormone and prolactin: characterized by bioassay, radioimmunoassay, radioreceptor assay, and electrophoresis
Human GH (hGH) and PRL (hPRL) were iodinated using lactoperoxidase. The iodinated hormones were characterized by RIA, radioreceptor assay (RRA), and bioassay (BA) using the Nb2 Node lymphoma cell line. The proportion of tracer that could bind to rat liver membranes or rabbit antibodies was determined, and the distribution of iodinated hormones was examined using polyacrylamide gel electrophoresis. Excess antibody was capable of precipitating 87.9% of the radioactivity associated with the hGH tracer and 86.0% of the hPRL tracer. The maximal specific binding to a liver membrane preparation averaged 67.3% of the (/sup 125/I)iodo-hGH radioactivity and 48.8% of the (/sup 125/I)iodo-hPRL radioactivity. The respective BA and RRA activity estimates for (/sup 125/I)iodo-hGH averaged 90% and 114% of the activity measured by the RIA. For (/sup 125/I)iodo-hPRL, the values were 75% by BA and 68% by RRA. The bioactivity profiles of iodinated hGH and hPRL shifted anodally on polyacrylamide gel electrophoresis in comparison to the bioactivity distribution of the respective uniodinated hormones. Iodine incorporation rather than oxidation appeared to be responsible for the shift. After electrophoresis, all eluates which contained significant radioactivity were active in the BA and RIA. Furthermore, specific activities calculated from the bioactive hormone and radioactivity in each electrophoretic segment agreed well with the average specific activity estimated from the amount of iodine incorporated into the protein peak upon gel filtration. These data suggest that hGH and hPRL to a major degree retain biological integrity after iodination.
- Research Organization:
- Department of Physiology, University of Manitoba, Winnipeg, Canada
- OSTI ID:
- 6586796
- Journal Information:
- Endocrinology; (United States), Vol. 111:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
IODINE 125
TRACER TECHNIQUES
LTH
BIOCHEMICAL REACTION KINETICS
RADIOIMMUNOASSAY
STH
CHEMICAL PREPARATION
IODINATION
PHYSIOLOGY
RABBITS
RATS
ANIMALS
BETA DECAY RADIOISOTOPES
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
GONADOTROPINS
HALOGENATION
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
PEPTIDE HORMONES
PITUITARY HORMONES
RADIOASSAY
RADIOISOTOPES
REACTION KINETICS
RODENTS
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques
551001 - Physiological Systems- Tracer Techniques