Synthesis and binding affinity of an iodinated juvenile hormone
The synthesis of the first iodinated juvenile hormone (JH) in enantiomerically enriched form is reported. This chiral compound, 12-iodo-JH I, has an iodine atom replacing a methyl group of the natural insect juvenile hormone, JH I, which is important in regulating morphogenesis and reproduction in the Lepidoptera. The unlabeled compound shows approximately 10% of the relative binding affinity for the larval hemolymph JH binding protein (JHBP) of Manduca sexta, which specifically binds natural /sup 3/H-10R,11S-JH I (labeled at 58 Ci/mmol) with a KD of 8 X 10(-8) M. It is also approximately one-tenth as biologically active as JH I in the black Manduca and epidermal commitment assays. The 12-hydroxy and 12-oxo compounds are poor competitors and are also biologically inactive. The radioiodinated (/sup 125/I)12-iodo-JH I can be prepared in low yield at greater than 2500 Ci/mmol by nucleophilic displacement using no-carrier-added /sup 125/I-labeled sodium iodide in acetone; however, synthesis using sodium iodide carrier to give the approximately 50 Ci/mmol radioiodinated ligand proceeds in higher radiochemical yield with fewer by-products and provides a radioligand which is more readily handled in binding assays. The KD of (/sup 125/I)12-iodo-JH I was determined for hemolymph JHBP of three insects: M. sexta, 795 nM; Galleria mellonella, 47 nM; Locusta migratoria, 77 nM. The selectivity of 12-iodo-JH I for the 32-kDa JHBP of M. sexta was demonstrated by direct autoradiography of a native polyacrylamide gel electrophoresis gel of larval hemolymph incubated with the radioiodinated ligand. Thus, the in vitro and in vivo activity of 12-iodo-JH I indicate that it can serve as an important new gamma-emitting probe in the search for JH receptor proteins in target tissues.
- Research Organization:
- State Univ. of New York, Stony Brook
- OSTI ID:
- 5640618
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 263:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HORMONES
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
AFFINITY
AUTORADIOGRAPHY
ELECTROPHORESIS
IODINE 125
LARVAE
LEPIDOPTERA
LIGANDS
TRITIUM COMPOUNDS
ANIMALS
ARTHROPODS
BETA DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
INSECTS
INTERMEDIATE MASS NUCLEI
INVERTEBRATES
IODINE ISOTOPES
ISOTOPES
KINETICS
LABELLED COMPOUNDS
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
REACTION KINETICS
SYNTHESIS
550201* - Biochemistry- Tracer Techniques