Biomaterial Database

The use of homologous and heterologous 125I-radioligands in the radioimmunoassay of progesterone. 1978

R M Allen, and M R Redshaw

Eight homologous and heterologous 125I-radioligand systems for the radioimmunoassay of progesterone were examined. Using an antiserum raised to 11alpha-hydroxyprogesterone 11-succinyl-bovine serum albumin, standard curves were set up with the homologous radioligands, 11alpha-hydroxyprogesterone 11-succinyl-[125I]-iodotyramine, -[125I]-iodohistamine and -[125I]-iodotyrosine methyl ester. Heterologous bridge systems were represented by progesterone-11alpha-oxycarbonyl-[125I]-iodotyrosine methyl ester and 11alpha-hydroxyprogesterone 11-phthalyl-[125I]-iodotyrosine methyl ester, and heterologous site systems by progesterone-3-(O-carboxymethyl)oxime-[125I]-iodotyramine, progesterone-12-(O-carboxymethyl)oxime-[125I]-iodotyramine, and progesterone-20-(O-carboxymethyl)oxime-[125I]-iodohistamine. The preparation of the steroid derivatives and iodination by a two-phase method are described. The curves obtained from the homologous radioligands were relatively insensitive compared with a tritiated system, with the tyrosine methyl ester derivative providing a more sensitive assay than the corresponding tyramine or histamine analogues. The heterologous bridge systems gave more sensitive curves than the homologous tracers whilst the 3- and 12-(O-carboxymethyl)oxime derivatives of progesterone furnished curves as sensitive as the tritiated reference. Progesterone-20-(O-carboxymethyl)oxime-[125I]-iodohistamine was not bound by the antibody.

UI	MeSH Term	Description	Entries
D007457	Iodine Radioisotopes	Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.	Radioisotopes, Iodine
D008024	Ligands	A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)	Ligand
D011374	Progesterone	The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS.	Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D011863	Radioimmunoassay	Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.	Radioimmunoassays
D012710	Serum Albumin, Bovine	Serum albumin from cows, commonly used in in vitro biological studies. (From Stedman, 25th ed)	Fetal Bovine Serum,Fetal Calf Serum,Albumin Bovine,Bovine Albumin,Bovine Serum Albumin,Albumin, Bovine,Albumin, Bovine Serum,Bovine Serum, Fetal,Bovine, Albumin,Calf Serum, Fetal,Serum, Fetal Bovine,Serum, Fetal Calf
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships