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Application of a sequence-specific radioimmunoassay for the carboxyl-terminal region of corticotropin.

Authors
Type
Published Article
Journal
Clinical chemistry
Publication Date
Volume
27
Issue
4
Pages
549–552
Identifiers
PMID: 6162590
Source
Medline
License
Unknown

Abstract

The carboxyl terminal region of corticotropin (ACTH), (Ala34-Phe-Pro-Glu-Leu-Phe39), a region of the hormone conserved during evolution, served as an antigen for the production of a sequence-specific antiserum. In a radioimmunoassay, peptides that extend toward the amino terminal from Ala34, such as [Tyr,Gly]-ACTH34-39, ACTH18-39, and ACTH, had greater affinity for the antibody, which suggests that the antiserum recognizes the peptide bond preceding the alanyl residue. The assay readily detects 30 to 50 pmol of ACTH per liter with an incubation of only 3 h, and the antiserum cross reacts with larger molecular mass forms of the hormone. The amount of immunoreactive ACTH extracted by adsorption onto silicic acid from rat and human plasma was only 0.36 to 0.79 of that detected by a mid-region ACTH assay, which suggests proteolytic degradation at the carboxyl terminus of ACTH.

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