Open AccessJuvenile‐hormone‐binding protein from the hemolymph of Galleria mellonella (L)
Author(s) -
OżYHAR Andrzej,
KOCHMAN Marian
Publication year - 1987
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1987.tb10690.x
Subject(s) - chromatofocusing , isoelectric point , hemolymph , chemistry , chromatography , size exclusion chromatography , isoelectric focusing , dissociation constant , biochemistry , receptor , enzyme
A juvenile‐hormone‐binding protein (JHBP) has been isolated from Galleria mellonella hemolymph by gel filtration, phosphocellulose chromatography, and by chromatofocusing. The isolated protein is homogenous as judged by column chromatography and gel electrophoresis in the presence and absence of denaturing agent. It has a relative molecular mass of 32000, Stokes radius 2.4 nm, sedimentation coefficient of 2.3 S, molar absorption coefficient at 280 nm ɛ= 2.34 × 10 4 M ‐1 cm ‐1 , and is composed of a single polypeptide chain. Chromatofocusing analysis (pI 8.6) and isoelectric focusing (pI 8.1) indicate that the JHBP is an alkaline protein. Its amino acid composition and fluorescence absorption spectra indicate that the protein does not contain tryptophan residues. The protein exhibits one class of binding sites for juvenile hormone (JH), 0.8 per molecule, with the following dissociation constants: JH I, 8.5 × 10 ‐8 M; JH II, 7.2 × 10 ‐8 M; JH III, 47 × 10 ‐8 M. The JHBP binds (10 R , 11 S )‐JH II enantiomer with 2.3‐times higher affinity then (10 S , 11 R )‐JH II enantiomer. The pH optimum of binding is 7.0.